Transports: Raise FileNotFoundError in copy if source doesn't exist

The `LocalTransport` and `SshTransport` would raise a generic `OSError`
which would make it to distinguish the problem of the source not
existing from an more serious problem like the operation failing.
The methods now make sure to throw a `FileNotFoundError` if the source
doesn't exist.

aiida/transports/plugins/local.py

@@ -557,7 +557,7 @@ def copy(self, remotesource, remotedestination, dereference=False, recursive=Tru
             raise ValueError('Input remotedestination to copy must be a non empty object')
         if not self.has_magic(remotesource):
             if not os.path.exists(os.path.join(self.curdir, remotesource)):
-                raise OSError('Source not found')
+                raise FileNotFoundError('Source not found')
         if self.normalize(remotesource) == self.normalize(remotedestination):
             raise ValueError('Cannot copy from itself to itself')
 

aiida/transports/plugins/ssh.py

@@ -1203,6 +1203,7 @@ def copy(self, remotesource, remotedestination, dereference=False, recursive=Tru
             raise ValueError('Pathname patterns are not allowed in the destination')
 
         if self.has_magic(remotesource):
+
             to_copy_list = self.glob(remotesource)
 
             if len(to_copy_list) > 1:
@@ -1213,6 +1214,9 @@ def copy(self, remotesource, remotedestination, dereference=False, recursive=Tru
                 self._exec_cp(cp_exe, cp_flags, file, remotedestination)
 
         else:
+            if not self.path_exists(remotesource):
+                raise FileNotFoundError('Source not found')
+
             self._exec_cp(cp_exe, cp_flags, remotesource, remotedestination)
 
     def _exec_cp(self, cp_exe, cp_flags, src, dst):