A git pathspec is a filename, except when it starts with ':', it's taken
to refer to a branch, etc. Rather than special case ':', any filename
starting with anything unusual is prefixed with "./"
This could have been a real mess to deal with, but luckily SafeCommand
is already extensively used and so we know at the type level the difference
between parameters that are files, and parameters that are command options.
Testing did show that Git.Queue was not using SafeCommand on
filenames fed to xargs. (Filenames starting with '-' worked before only
because -- was used to separate filenames from options when calling eg git
add.)
The test suite now passes with filenames starting with ':'. However, I did
not keep that change to it, because such filenames are probably not legal
on windows, and I have enough ugly windows ifdefs in there as it is.
This commit was sponsored by Otavio Salvador. Thanks!
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