Re: [PATCH] completion: fix completion after 'git -C path'

> The main completion function finds the name of the git command by
> iterating through all the words on the command line in search for the
> first non-option-looking word.  As it is not aware of 'git -C's
> mandatory path argument, if the '-C path' option is present, 'path' will
> be the first such word and it will be mistaken for a git command.  This
> breaks the completion script in various ways:
> 
>  - If 'path' happens to match one of the commands supported by the
>    completion script, then its options will be offered.
> 
>  - If 'path' doesn't match a supported command and doesn't contain any
>    characters not allowed in Bash identifier names, then the completion
>    script does basically nothing and lets Bash to fall back to filename
>    completion.
> 
>  - Otherwise, if 'path' contains such unallowed characters, then it
>    leads to a more or less ugly error in the middle of the command line.
>    The standard '/' directory separator is such a character, and it
>    happens to trigger one of the uglier errors:
> 
>      $ git -C some/path <TAB>sh.exe": declare: `_git_some/path': not a valid identifier
>      error: invalid key: alias.some/path
> 
> Fix this by skipping 'git -C's mandatory path argument while iterating
> over the words on the command line.  Extend the relevant test with this
> case and, while at it, with cases that needed similar treatment in the
> past ('--git-dir', '-c', '--work-tree' and '--namespace').
> Additionally, shut up standard error of the 'declare' commands looking
> for the associated completion function and of the 'git config' query for
> the aliased command, so if git learns a new option with a mandatory
> argument in the future, then at least the command line will not be
> utterly disrupted by those error messages.
> 
> Note, that this change merely fixes the breakage related to 'git -C
> path', but the completion script will not take it into account as it
> does '--git-dir path'.