Re: [PATCH v2 1/1] p4 unshelve: fix "Not a valid object name HEAD0" on Windows

[Junio C Hamano <gitster@pobox.com>]

"Mike Mueller via GitGitGadget" <gitgitgadget@gmail.com> writes:

> From: Mike Mueller <mike.mueller@moodys.com>
>
> git p4 unshelve was failing with these errors:
>
> fatal: Not a valid object name HEAD0
> Command failed: git cat-file commit HEAD^0
>
> (git version 2.21.0.windows.1, python 2.7.16)
>
> The pOpen call used by git-p4 to invoke the git command can take either a
> string or an array as a first argument. The array form is preferred
> because platform-specific escaping of special characters will be
> handled automatically.(https://docs.python.org/2/library/subprocess.html)
> The extractLogMessageFromGitCommit method was, however, using the string
> form and so the caret (^) character in the HEAD^0 argument was not being
> escaped on Windows.  The caret happens to be the escape character, which
> is why the git command was receiving HEAD0.

In the output from

    git grep 'read_pipe_lines("'

together with a few hits to harmless constant command line, we find
this line

    diff = read_pipe_lines("git diff-tree -r %s \"%s^\" \"%s\"" % (self.diffOpts, id, id))

Would the caret we see there cause a similar problem?  It would end
up running something like

   $ git diff-tree -r -M "HEAD^" "HEAD"