help: provide help of bad alias without executing aliascmd()
The output is slightly changed because of minirst formatting. Previously,
ui.pushbuffer() had no effect because "badalias" message was written to stderr.
"if not unknowncmd" should no longer be needed because there's no call loop.
basic test for hg debugrebuildstate
$ hg init repo
$ cd repo
$ touch foo bar
$ hg ci -Am 'add foo bar'
adding bar
adding foo
$ touch baz
$ hg add baz
$ hg rm bar
$ hg debugrebuildstate
state dump after
$ hg debugstate --nodates | sort
n 644 -1 bar
n 644 -1 foo
status
$ hg st -A
! bar
? baz
C foo
$ cd ..