tests/notcapable

patchbomb: fix traceback on outgoing when not specifying revisions

A user reported that `hg email -n -o` raised with the following traceback:

```
** unknown exception encountered, please report by visiting
** https://mercurial-scm.org/wiki/BugTracker
** Python 3.8.12 (default, Sep 13 2021, 22:12:54) [GCC 7.5.0]
** Mercurial Distributed SCM (version 5.9.1)
** Extensions loaded: patchbomb
Traceback (most recent call last):
  File "/usr/pkg/bin/hg", line 61, in <module>
    dispatch.run()
  File "/usr/pkg/lib/python3.8/site-packages/mercurial/dispatch.py", line 144, in run
    status = dispatch(req)
  File "/usr/pkg/lib/python3.8/site-packages/mercurial/dispatch.py", line 250, in dispatch
    status = _rundispatch(req)
  File "/usr/pkg/lib/python3.8/site-packages/mercurial/dispatch.py", line 294, in _rundispatch
    ret = _runcatch(req) or 0
  File "/usr/pkg/lib/python3.8/site-packages/mercurial/dispatch.py", line 470, in _runcatch
    return _callcatch(ui, _runcatchfunc)
  File "/usr/pkg/lib/python3.8/site-packages/mercurial/dispatch.py", line 480, in _callcatch
    return scmutil.callcatch(ui, func)
  File "/usr/pkg/lib/python3.8/site-packages/mercurial/scmutil.py", line 153, in callcatch
    return func()
  File "/usr/pkg/lib/python3.8/site-packages/mercurial/dispatch.py", line 460, in _runcatchfunc
    return _dispatch(req)
  File "/usr/pkg/lib/python3.8/site-packages/mercurial/dispatch.py", line 1273, in _dispatch
    return runcommand(
  File "/usr/pkg/lib/python3.8/site-packages/mercurial/dispatch.py", line 918, in runcommand
    ret = _runcommand(ui, options, cmd, d)
  File "/usr/pkg/lib/python3.8/site-packages/mercurial/dispatch.py", line 1285, in _runcommand
    return cmdfunc()
  File "/usr/pkg/lib/python3.8/site-packages/mercurial/dispatch.py", line 1271, in <lambda>
    d = lambda: util.checksignature(func)(ui, *args, **strcmdopt)
  File "/usr/pkg/lib/python3.8/site-packages/mercurial/util.py", line 1886, in check
    return func(*args, **kwargs)
  File "/usr/pkg/lib/python3.8/site-packages/hgext/patchbomb.py", line 817, in email
    revs = _getoutgoing(repo, dest, revs)
  File "/usr/pkg/lib/python3.8/site-packages/hgext/patchbomb.py", line 537, in _getoutgoing
    safe_paths = [urlutil.hidepassword(p.rawloc) for p in paths]
  File "/usr/pkg/lib/python3.8/site-packages/hgext/patchbomb.py", line 537, in <listcomp>
    safe_paths = [urlutil.hidepassword(p.rawloc) for p in paths]
  File "/usr/pkg/lib/python3.8/site-packages/mercurial/utils/urlutil.py", line 501, in get_push_paths
    msg %= dest
TypeError: %b requires a bytes-like object, or an object that implements __bytes__, not 'NoneType'
```

This is due to patchbomb passing `[None]` in the `dests` parameter of the
multi-paths outgoing function, we fix this in this change and add a
non-regression test.

Differential Revision: https://phab.mercurial-scm.org/D11456

# Disable the $CAP wire protocol capability.

if test -z "$CAP"
then
    echo "CAP environment variable not set."
fi

cat > notcapable-$CAP.py << EOF
from mercurial import extensions, localrepo
from mercurial.interfaces import repository
def extsetup(ui):
    extensions.wrapfunction(repository.peer, 'capable', wrapcapable)
    extensions.wrapfunction(localrepo.localrepository, 'peer', wrappeer)
def wrapcapable(orig, self, name, *args, **kwargs):
    if name in b'$CAP'.split(b' '):
        return False
    return orig(self, name, *args, **kwargs)
def wrappeer(orig, self):
    # Since we're disabling some newer features, we need to make sure local
    # repos add in the legacy features again.
    return localrepo.locallegacypeer(self)
EOF

echo '[extensions]' >> $HGRCPATH
echo "notcapable-$CAP = `pwd`/notcapable-$CAP.py" >> $HGRCPATH