[BUG] typo DWIMery with alias broken (cd to random dir)

[Michael J Gruber <git@drmicha.warpmail.net>]

Hi there,

with current next (989ee58 plus local additions) it seems that typo
DWIMery with aliases is broken, see below.

It appears that the typo DWIMery is broken only when there is a unique
automatic DWIM substitution for a mistyped alias.

I haven't bisected yet, but I suspect this to be related to recent
changes regarding the environment in which commands/aliases are started
(though this happens without extra work trees), so I'm cc'ing an expert
in that area. Funny, though, that my user name shows up...

I think the reason is that git.c's handle_alias() (or something else)
calls restore_env() multiple times, and restore_env frees orig_cwd such
that subsequent restore_env(0) with external_alias=0 tries to cd to a
random location.

I have no idea whether orig_cwd=0 after freeing or something else would
be the proper fix.

Michael

LANG=C git sss
WARNING: You called a Git command named 'sss', which does not exist.
Continuing under the assumption that you meant 'ss'
in 2.0 seconds automatically...
fatal: could not move to git@drmicha.warpmail.net: No such file or directory
[mjg@skimbleshanks git]✗ LANG=C git ss
## HEAD (no branch)
?? a
?? a.patch
?? c2d.sh
[mjg@skimbleshanks git]✓ LANG=C git statu -sb
git: 'statu' is not a git command. See 'git --help'.

Did you mean one of these?
        status
        stage
        stash
[mjg@skimbleshanks git]✗ LANG=C git statuss -sb
WARNING: You called a Git command named 'statuss', which does not exist.
Continuing under the assumption that you meant 'status'
in 2.0 seconds automatically...
## HEAD (no branch)
?? a
?? a.patch
?? c2d.sh