(Rust) Error in Rust Snap Creation Tutorial

[omairqazi]

While following the tutorial (https://docs.snapcraft.io/build-snaps/rust), I faced the following issues in:

1. Trying to snapcraft the parity repo (https://github.com/snapcraft-docs/parity)
   Error :

"grade" property not specified: defaulting to "stable"
Preparing to pull parity 
Hit http://in.archive.ubuntu.com/ubuntu xenial InRelease                       
Get:1 http://security.ubuntu.com/ubuntu xenial-security InRelease [102 kB]     
Get:2 http://in.archive.ubuntu.com/ubuntu xenial-updates InRelease [102 kB]    
Get:3 http://in.archive.ubuntu.com/ubuntu xenial-backports InRelease [102 kB]  
Fetched 306 kB in 0s (0 B/s)                                                   
Ignoring already existing file: /home/omair/.cache/snapcraft/stage-packages/apt/de35704132271e996a92da9a657764dfba67f6987d4e8eff4c6ba0c75ecc9a88d11a1be61a7c38939259217078b4037c/var/cache/apt/archives/gcc-6-base_6.0.1-0ubuntu1_amd64.deb
Ignoring already existing file: /home/omair/.cache/snapcraft/stage-packages/apt/de35704132271e996a92da9a657764dfba67f6987d4e8eff4c6ba0c75ecc9a88d11a1be61a7c38939259217078b4037c/var/cache/apt/archives/libudev1_229-4ubuntu21_amd64.deb
Ignoring already existing file: /home/omair/.cache/snapcraft/stage-packages/apt/de35704132271e996a92da9a657764dfba67f6987d4e8eff4c6ba0c75ecc9a88d11a1be61a7c38939259217078b4037c/var/cache/apt/archives/libstdc++6_5.4.0-6ubuntu1~16.04.5_amd64.deb
Ignoring already existing file: /home/omair/.cache/snapcraft/stage-packages/apt/de35704132271e996a92da9a657764dfba67f6987d4e8eff4c6ba0c75ecc9a88d11a1be61a7c38939259217078b4037c/var/cache/apt/archives/libssl1.0.0_1.0.2g-1ubuntu4.10_amd64.deb
Pulling parity 
Traceback (most recent call last):
 File "/usr/lib/python3/dist-packages/urllib3/connection.py", line 137, in _new_conn
   (self.host, self.port), self.timeout, **extra_kw)
 File "/usr/lib/python3/dist-packages/urllib3/util/connection.py", line 67, in create_connection
   for res in socket.getaddrinfo(host, port, 0, socket.SOCK_STREAM):
 File "/usr/lib/python3.5/socket.py", line 732, in getaddrinfo
   for res in _socket.getaddrinfo(host, port, family, type, proto, flags):
socket.gaierror: [Errno -2] Name or service not known

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
 File "/usr/lib/python3/dist-packages/urllib3/connectionpool.py", line 560, in urlopen
   body=body, headers=headers)
 File "/usr/lib/python3/dist-packages/urllib3/connectionpool.py", line 346, in _make_request
   self._validate_conn(conn)
 File "/usr/lib/python3/dist-packages/urllib3/connectionpool.py", line 787, in _validate_conn
   conn.connect()
 File "/usr/lib/python3/dist-packages/urllib3/connection.py", line 217, in connect
   conn = self._new_conn()
 File "/usr/lib/python3/dist-packages/urllib3/connection.py", line 146, in _new_conn
   self, "Failed to establish a new connection: %s" % e)
requests.packages.urllib3.exceptions.NewConnectionError: <requests.packages.urllib3.connection.VerifiedHTTPSConnection object at 0x7f8485106ba8>: Failed to establish a new connection: [Errno -2] Name or service not known

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
 File "/usr/lib/python3/dist-packages/requests/adapters.py", line 376, in send
   timeout=timeout
 File "/usr/lib/python3/dist-packages/urllib3/connectionpool.py", line 610, in urlopen
   _stacktrace=sys.exc_info()[2])
 File "/usr/lib/python3/dist-packages/urllib3/util/retry.py", line 273, in increment
   raise MaxRetryError(_pool, url, error or ResponseError(cause))
requests.packages.urllib3.exceptions.MaxRetryError: HTTPSConnectionPool(host='static.rust-lang.org', port=443): Max retries exceeded with url: /rustup.sh (Caused by NewConnectionError('<requests.packages.urllib3.connection.VerifiedHTTPSConnection object at 0x7f8485106ba8>: Failed to establish a new connection: [Errno -2] Name or service not known',))

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
 File "/usr/bin/snapcraft", line 9, in <module>
   load_entry_point('snapcraft==2.35', 'console_scripts', 'snapcraft')()
 File "/usr/lib/python3/dist-packages/pkg_resources/__init__.py", line 542, in load_entry_point
   return get_distribution(dist).load_entry_point(group, name)
 File "/usr/lib/python3/dist-packages/pkg_resources/__init__.py", line 2569, in load_entry_point
   return ep.load()
 File "/usr/lib/python3/dist-packages/pkg_resources/__init__.py", line 2229, in load
   return self.resolve()
 File "/usr/lib/python3/dist-packages/pkg_resources/__init__.py", line 2235, in resolve
   module = __import__(self.module_name, fromlist=['__name__'], level=0)
 File "/usr/lib/python3/dist-packages/snapcraft/cli/__main__.py", line 19, in <module>
   run(prog_name='snapcraft')
 File "/usr/lib/python3/dist-packages/click/core.py", line 716, in __call__
   return self.main(*args, **kwargs)
 File "/usr/lib/python3/dist-packages/click/core.py", line 696, in main
   rv = self.invoke(ctx)
 File "/usr/lib/python3/dist-packages/click/core.py", line 1037, in invoke
   return Command.invoke(self, ctx)
 File "/usr/lib/python3/dist-packages/click/core.py", line 889, in invoke
   return ctx.invoke(self.callback, **ctx.params)
 File "/usr/lib/python3/dist-packages/click/core.py", line 534, in invoke
   return callback(*args, **kwargs)
 File "/usr/lib/python3/dist-packages/click/decorators.py", line 17, in new_func
   return f(get_current_context(), *args, **kwargs)
 File "/usr/lib/python3/dist-packages/snapcraft/cli/__init__.py", line 124, in run
   ctx.forward(lifecyclecli.commands['snap'])
 File "/usr/lib/python3/dist-packages/click/core.py", line 552, in forward
   return self.invoke(cmd, **kwargs)
 File "/usr/lib/python3/dist-packages/click/core.py", line 534, in invoke
   return callback(*args, **kwargs)
 File "/usr/lib/python3/dist-packages/snapcraft/cli/lifecycle.py", line 140, in snap
   project_options, directory=directory, output=output)
 File "/usr/lib/python3/dist-packages/snapcraft/internal/lifecycle/_packer.py", line 45, in snap
   execute('prime', project_options)
 File "/usr/lib/python3/dist-packages/snapcraft/internal/lifecycle/_runner.py", line 80, in execute
   _Executor(config, project_options).run(step, part_names)
 File "/usr/lib/python3/dist-packages/snapcraft/internal/lifecycle/_runner.py", line 175, in run
   self._run_step(step, part, part_names)
 File "/usr/lib/python3/dist-packages/snapcraft/internal/lifecycle/_runner.py", line 212, in _run_step
   getattr(part, step)()
 File "/usr/lib/python3/dist-packages/snapcraft/internal/pluginhandler/__init__.py", line 252, in pull
   self.plugin.pull()
 File "/usr/lib/python3/dist-packages/snapcraft/plugins/rust.py", line 180, in pull
   self._fetch_rust()
 File "/usr/lib/python3/dist-packages/snapcraft/plugins/rust.py", line 210, in _fetch_rust
   self._rustup_get.download()
 File "/usr/lib/python3/dist-packages/snapcraft/internal/sources/_script.py", line 31, in download
   super().download()
 File "/usr/lib/python3/dist-packages/snapcraft/internal/sources/_base.py", line 92, in download
   self.source, stream=True, allow_redirects=True)
 File "/usr/lib/python3/dist-packages/requests/api.py", line 67, in get
   return request('get', url, params=params, **kwargs)
 File "/usr/lib/python3/dist-packages/requests/api.py", line 53, in request
   return session.request(method=method, url=url, **kwargs)
 File "/usr/lib/python3/dist-packages/requests/sessions.py", line 468, in request
   resp = self.send(prep, **send_kwargs)
 File "/usr/lib/python3/dist-packages/requests/sessions.py", line 576, in send
   r = adapter.send(request, **kwargs)
 File "/usr/lib/python3/dist-packages/requests/adapters.py", line 437, in send
   raise ConnectionError(e, request=request)
requests.exceptions.ConnectionError: HTTPSConnectionPool(host='static.rust-lang.org', port=443): Max retries exceeded with url: /rustup.sh (Caused by NewConnectionError('<requests.packages.urllib3.connection.VerifiedHTTPSConnection object at 0x7f8485106ba8>: Failed to establish a new connection: [Errno -2] Name or service not known',)) 

2. Installing the snap
   Error:
   error: cannot open: "parity_*.snap"
3. Running the snap
   Error:

No command 'parity' found, did you mean:
 Command 'purity' from package 'purity' (universe)
parity: command not found

The errors (2) and (3) are obvious as the package was not snapcrafted but new users following this tutorial will get confused.