friendly error messages if update fails

[canavan]

If an update via -U fails, a stack trace is printed. A friendlier error message with a clear indication what failed (e.g. a timeout), would be nice.

$ youtube-dl --verbose -U
[debug] System config: []
[debug] User config: []
[debug] Command-line args: [u'--verbose', u'-U']
[debug] Encodings: locale ISO8859-1, fs ISO8859-1, out ISO8859-1, pref ISO8859-1
[debug] youtube-dl version 2015.12.06
[debug] Python version 2.7.11 - IRIX64-6.5-IP35-mips-n32bit-ELF
[debug] exe versions: ffmpeg UNKNOWN, ffprobe UNKNOWN, rtmpdump 2.2b
[debug] Proxy map: {'http': 'http://10.2.4.16:3128/', u'https': 'http://10.2.4.16:3128/'}
Updating to version 2016.01.01 ...
Traceback (most recent call last):
File "/usr/nekoware/lib/python2.7/runpy.py", line 162, in _run_module_as_main
"main", fname, loader, pkg_name)
File "/usr/nekoware/lib/python2.7/runpy.py", line 72, in _run_code
exec code in run_globals
File "/usr/nekoware/bin/youtube-dl/main.py", line 19, in
File "/usr/nekoware/bin/youtube-dl/youtube_dl/init.py", line 410, in main
File "/usr/nekoware/bin/youtube-dl/youtube_dl/init.py", line 380, in _real_main
File "/usr/nekoware/bin/youtube-dl/youtube_dl/update.py", line 167, in update_self
File "/usr/nekoware/lib/python2.7/urllib2.py", line 431, in open
response = self._open(req, data)
File "/usr/nekoware/lib/python2.7/urllib2.py", line 449, in _open
'_open', req)
File "/usr/nekoware/lib/python2.7/urllib2.py", line 409, in _call_chain
result = func(*args)
File "/usr/nekoware/bin/youtube-dl/youtube_dl/utils.py", line 813, in https_open
File "/usr/nekoware/lib/python2.7/urllib2.py", line 1200, in do_open
r = h.getresponse(buffering=True)
File "/usr/nekoware/lib/python2.7/httplib.py", line 1136, in getresponse
response.begin()
File "/usr/nekoware/lib/python2.7/httplib.py", line 453, in begin
version, status, reason = self._read_status()
File "/usr/nekoware/lib/python2.7/httplib.py", line 417, in _read_status
raise BadStatusLine(line)
httplib.BadStatusLine: ''

[dstftw]

This is what returned by your proxy.

[canavan]

Without --verbose, the cause of the problem is not printed, even if no proxy is used:

$ http_proxy= youtube-dl -U
Updating to version 2016.01.01 ...
ERROR: unable to download latest version

with --verbose:

$ http_proxy= youtube-dl -U --verbose
[debug] System config: []
[debug] User config: []
[debug] Command-line args: [u'-U', u'--verbose']
[debug] Encodings: locale ISO8859-1, fs ISO8859-1, out ISO8859-1, pref ISO8859-1
[debug] youtube-dl version 2015.12.06
[debug] Python version 2.7.11 - IRIX64-6.5-IP35-mips-n32bit-ELF
[debug] exe versions: ffmpeg UNKNOWN, ffprobe UNKNOWN, rtmpdump 2.2b
[debug] Proxy map: {}
Updating to version 2016.01.01 ...
Traceback (most recent call last):
File "/usr/nekoware/bin/youtube-dl/youtube_dl/update.py", line 167, in update_self
urlh = opener.open(version['bin'][0])
File "/usr/nekoware/lib/python2.7/urllib2.py", line 431, in open
response = self._open(req, data)
File "/usr/nekoware/lib/python2.7/urllib2.py", line 449, in _open
'_open', req)
File "/usr/nekoware/lib/python2.7/urllib2.py", line 409, in _call_chain
result = func(_args)
File "/usr/nekoware/bin/youtube-dl/youtube_dl/utils.py", line 813, in https_open
req, *_kwargs)
File "/usr/nekoware/lib/python2.7/urllib2.py", line 1197, in do_open
raise URLError(err)
URLError: <urlopen error [Errno 145] Connection timed out>

ERROR: unable to download latest version