tests/test-archive-symlinks.t

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

#require symlink

  $ origdir=`pwd`

  $ hg init repo
  $ cd repo
  $ ln -s nothing dangling

avoid tar warnings about old timestamp

  $ hg ci -d '2000-01-01 00:00:00 +0000' -qAm 'add symlink'

  $ hg archive -t files ../archive
  $ hg archive -t tar -p tar ../archive.tar
  $ hg archive -t zip -p zip ../archive.zip

files

  $ cd "$origdir"
  $ cd archive
  $ readlink.py dangling
  dangling -> nothing

tar

  $ cd "$origdir"
  $ tar xf archive.tar
  $ cd tar
  $ readlink.py dangling
  dangling -> nothing

#if unziplinks
zip

  $ cd "$origdir"
  $ unzip archive.zip > /dev/null 2>&1
  $ cd zip
  $ readlink.py dangling
  dangling -> nothing
#endif

  $ cd ..