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

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

Hi Junio,

On Tue, 28 May 2019, Junio C Hamano wrote:

> "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"

I think you're right!

In addition, I wonder whether we would want to replace the `^` by a `~`,
which would have the same effect, but does not need quoting in Bash nor
CMD.

Ciao,
Dscho