Make --no-ext-diff disable diff.<driver>.process in addition to
diff.<driver>.command. Although the two mechanisms work differently
(command replaces Git's output, process feeds hunks back into the
pipeline), both invoke external tools and --no-ext-diff means
"no external tools."
Replace the OPT_BOOL for --ext-diff with an OPT_CALLBACK that
sets both allow_external and no_diff_process, so a single option
controls both. Passing --ext-diff explicitly clears
no_diff_process, so a later --ext-diff overrides an earlier
--no-ext-diff.
Disable the diff process unconditionally in format-patch so that
generated patches are always based on the builtin diff algorithm
and can be applied reliably by recipients who do not have the
external tool.
Document that --diff-algorithm also bypasses the diff process,
since it forces the builtin algorithm.
Signed-off-by: Michael Montalbo <mmontalbo@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
ac69d22b32