Re: [PATCH v2 1/2] subtree: fix the GIT_EXEC_PATH sanity check to work on Windows

"Johannes Schindelin via GitGitGadget" [off-list ref]
writes:

Sadly, this construct is non-portable, according to
https://pubs.opengroup.org/onlinepubs/009695399/utilities/test.html.
However, it does not matter in practice because we still first look
whether `$GIT_EXEC_PREFIX` is string-identical to the first component of
`$PATH`. This will give us the expected result everywhere but in Git for
Windows, and Git for Windows' own Bash _does_ handle the `-ef` operator.

OK.  That's somewhat subtle and possibly brittle, but let's see how
it goes.

Will queue.

Thanks.