bashcompletion: show available command-line switches for aliases
When auto-completing hg commands, aliases are listed, but not the available
switches for an alias, because `HGPLAIN=1` filters these out. Add a
`HGPLAINEXCEPT=alias` exception to resolve this.
We make heavy use of aliases that drive hg log with custom revsets, sorting and
the -G switch, but want our users to be able to auto-complete any additional
command-line switches.
Test issue2761
$ hg init
$ touch to-be-deleted
$ hg add
adding to-be-deleted
$ hg ci -m first
$ echo a > to-be-deleted
$ hg ci -m second
$ rm to-be-deleted
$ hg diff -r 0
Same issue, different code path
$ hg up -C
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ touch does-not-exist-in-1
$ hg add
adding does-not-exist-in-1
$ hg ci -m third
$ rm does-not-exist-in-1
$ hg diff -r 1