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

[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 on Windows:
>
> 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
> however the extractLogMessageFromGitCommit method was using the string
> form, which makes the caller responsible for escaping the command text
> appropriately (see https://docs.python.org/2/library/subprocess.html)

Rewrite the sentence that begin with "The array form is
preferred...", as it is somewhat unreadable.  "X is preferred
because Y; however Z was using the other one" would be
understandable.

> Somewhat ironically, the carat character is the escape character in

s/carat/caret/ everywhere.

> Windows and so should be escaped (HEAD^^0).  Without the extra carat, the
> OS was passing an escaped 0 to the git command instead, and the git
> command was rejecting the invalid object name "HEAD0"
>
> The behaviour can be confirmed by typing ECHO HEAD^0 at the command-
> prompt, which emits HEAD0.
>
> The solution is simply to use the array format of passing the command to
> fOpen, which is preferred and used in other parts of this code anyway.
>
> Signed-off-by: Mike Mueller <mike.mueller@moodys.com>
> ---
>  git-p4.py | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/git-p4.py b/git-p4.py
> index 5b79920f46..0b5bfcbc5e 100755
> --- a/git-p4.py
> +++ b/git-p4.py
> @@ -737,7 +737,7 @@ def extractLogMessageFromGitCommit(commit):
>  
>      ## fixme: title is first line of commit, not 1st paragraph.
>      foundTitle = False
> -    for log in read_pipe_lines("git cat-file commit %s" % commit):
> +    for log in read_pipe_lines(["git", "cat-file", "commit", commit]):
>         if not foundTitle:
>             if len(log) == 1:
>                 foundTitle = True