tests/test-diff-reverse.t

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

  $ hg init

  $ cat > a <<EOF
  > a
  > b
  > c
  > EOF
  $ hg ci -Am adda
  adding a

  $ cat > a <<EOF
  > d
  > e
  > f
  > EOF
  $ hg ci -m moda

  $ hg diff --reverse -r0 -r1
  diff -r 2855cdcfcbb7 -r 8e1805a3cf6e a
  --- a/a	Thu Jan 01 00:00:00 1970 +0000
  +++ b/a	Thu Jan 01 00:00:00 1970 +0000
  @@ -1,3 +1,3 @@
  -d
  -e
  -f
  +a
  +b
  +c

  $ cat >> a <<EOF
  > g
  > h
  > EOF
  $ hg diff --reverse --nodates
  diff -r 2855cdcfcbb7 a
  --- a/a
  +++ b/a
  @@ -1,5 +1,3 @@
   d
   e
   f
  -g
  -h

should show removed file 'a' as being added
  $ hg revert a
  $ hg rm a
  $ hg diff --reverse --nodates a
  diff -r 2855cdcfcbb7 a
  --- /dev/null
  +++ b/a
  @@ -0,0 +1,3 @@
  +d
  +e
  +f

should show added file 'b' as being removed
  $ echo b >> b
  $ hg add b
  $ hg diff --reverse --nodates b
  diff -r 2855cdcfcbb7 b
  --- a/b
  +++ /dev/null
  @@ -1,1 +0,0 @@
  -b