format-patch: generate MIME header as needed even when there is format.header

Earlier, the callchain from pretty_print_commit() down to pp_title_line()
had an unwarranted assumption that the presense of "after_subject"
parameter, means the caller has already output MIME headers for
attachments.  The parameter's primary purpose is to give extra header
lines the caller wants to place after pp_title_line() generates the
"Subject: " line.

This assumption does not hold when the user used the format.header
configuration variable to pass extra headers, and caused a message with
non-ASCII character to lack proper MIME headers (e.g.  8-bit CTE header).
The earlier logic also failed to suppress duplicated MIME headers when
"format-patch -s --attach" is asked for and the signer's name demanded
8-bit clean transport.

This patch fixes the logic by introducing a separate need_8bit_cte
parameter passed down the callchain.  This can have one of these values:

 -1 : we've already done MIME crap and we do not want to add extra header
      to say this is 8bit in pp_title_line();

  0 : we haven't done MIME and we have not seen anything that is 8bit yet;

  1 : we haven't done MIME and we have seen something that is 8bit;
      pp_title_line() must add MIME header.

It adds two tests by Jeff King who independently diagnosed this issue.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 6 insertions, 1 deletions

diff --git a/log-tree.c b/log-tree.c
index 1f3fcf1..dd94f39 100644
--- a/log-tree.c
+++ b/log-tree.c
@@ -146,6 +146,7 @@ void show_log(struct rev_info *opt, const char *sep)
 	int abbrev_commit = opt->abbrev_commit ? opt->abbrev : 40;
 	const char *extra;
 	const char *subject = NULL, *extra_headers = opt->extra_headers;
+	int need_8bit_cte = 0;
 
 	opt->loginfo = NULL;
 	if (!opt->verbose_header) {
@@ -214,6 +215,8 @@ void show_log(struct rev_info *opt, const char *sep)
 		if (opt->mime_boundary) {
 			static char subject_buffer[1024];
 			static char buffer[1024];
+
+			need_8bit_cte = -1; /* never */
 			snprintf(subject_buffer, sizeof(subject_buffer) - 1,
 				 "%s"
 				 "MIME-Version: 1.0\n"
@@ -282,9 +285,11 @@ void show_log(struct rev_info *opt, const char *sep)
 	 * And then the pretty-printed message itself
 	 */
 	strbuf_init(&msgbuf, 0);
+	if (need_8bit_cte >= 0)
+		need_8bit_cte = has_non_ascii(opt->add_signoff);
 	pretty_print_commit(opt->commit_format, commit, &msgbuf,
 			    abbrev, subject, extra_headers, opt->date_mode,
-			    has_non_ascii(opt->add_signoff));
+			    need_8bit_cte);
 
 	if (opt->add_signoff)
 		append_signoff(&msgbuf, opt->add_signoff);