tests/printenv.py

sshpeer: add a configurable hint for the ssh error message

Adding a possibility to configure error hint to be shown in the case of problems with SSH. Example of such hint can be "Please see http://company/internalwiki/ssh.html".

Test Plan:
- Ran hg pull with broken link and verified the output has no hint by default:

```
pulling from ssh://brokenrepository.com//repo
remote: ssh: Could not resolve hostname brokenrepository.com: Name or service not known
abort: no suitable response from remote hg!
```

- Run hg pull --config ui.ssherrorhint="Please see http://company/internalwiki/ssh.html":

```
pulling from ssh://brokenrepository.com//repo
remote: ssh: Could not resolve hostname brokenrepository.com: Name or service not known
abort: no suitable response from remote hg!
(Please see http://company/internalwiki/ssh.html)
```

Differential Revision: https://phab.mercurial-scm.org/D1431

#!/usr/bin/env python
#
# simple script to be used in hooks
#
# put something like this in the repo .hg/hgrc:
#
#     [hooks]
#     changegroup = python "$TESTDIR/printenv.py" <hookname> [exit] [output]
#
#   - <hookname> is a mandatory argument (e.g. "changegroup")
#   - [exit] is the exit code of the hook (default: 0)
#   - [output] is the name of the output file (default: use sys.stdout)
#              the file will be opened in append mode.
#
from __future__ import absolute_import
import os
import sys

try:
    import msvcrt
    msvcrt.setmode(sys.stdin.fileno(), os.O_BINARY)
    msvcrt.setmode(sys.stdout.fileno(), os.O_BINARY)
    msvcrt.setmode(sys.stderr.fileno(), os.O_BINARY)
except ImportError:
    pass

exitcode = 0
out = sys.stdout

name = sys.argv[1]
if len(sys.argv) > 2:
    exitcode = int(sys.argv[2])
    if len(sys.argv) > 3:
        out = open(sys.argv[3], "ab")

# variables with empty values may not exist on all platforms, filter
# them now for portability sake.
env = [(k, v) for k, v in os.environ.iteritems()
       if k.startswith("HG_") and v]
env.sort()

out.write("%s hook: " % name)
if os.name == 'nt':
    filter = lambda x: x.replace('\\', '/')
else:
    filter = lambda x: x
vars = ["%s=%s" % (k, filter(v)) for k, v in env]
out.write(" ".join(vars))
out.write("\n")
out.close()

sys.exit(exitcode)