send-email: Refuse to send cover-letter template subject

Every so often, someone sends out an unedited cover-letter template.
Add a simple check to send-email that refuses to send if the subject
contains "*** SUBJECT HERE ***", with an option --force to override.

Signed-off-by: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-send-email.perl

@@ -85,6 +85,7 @@ git send-email [options] <file | directory | rev-list options >
     --[no-]validate                * Perform patch sanity checks. Default on.
     --[no-]format-patch            * understand any non optional arguments as
                                      `git format-patch` ones.
+    --force                        * Send even if safety checks would prevent it.
 
 EOT
 	exit(1);
@@ -162,6 +163,7 @@ if ($@) {
 my ($quiet, $dry_run) = (0, 0);
 my $format_patch;
 my $compose_filename;
+my $force = 0;
 
 # Handle interactive edition of files.
 my $multiedit;
@@ -301,6 +303,7 @@ my $rc = GetOptions("sender|from=s" => \$sender,
 		    "validate!" => \$validate,
 		    "format-patch!" => \$format_patch,
 		    "8bit-encoding=s" => \$auto_8bit_encoding,
+		    "force" => \$force,
 	 );
 
 unless ($rc) {
@@ -702,6 +705,16 @@ if (!defined $auto_8bit_encoding && scalar %broken_encoding) {
 				  default => "UTF-8");
 }
 
+if (!$force) {
+	for my $f (@files) {
+		if (get_patch_subject($f) =~ /\*\*\* SUBJECT HERE \*\*\*/) {
+			die "Refusing to send because the patch\n\t$f\n"
+				. "has the template subject '*** SUBJECT HERE ***'. "
+				. "Pass --force if you really want to send.\n";
+		}
+	}
+}
+
 my $prompting = 0;
 if (!defined $sender) {
 	$sender = $repoauthor || $repocommitter || '';

t/t9001-send-email.sh

@@ -995,4 +995,40 @@ test_expect_success '--8bit-encoding also treats subject' '
 	test_cmp expected actual
 '
 
+# Note that the patches in this test are deliberately out of order; we
+# want to make sure it works even if the cover-letter is not in the
+# first mail.
+test_expect_success 'refusing to send cover letter template' '
+	clean_fake_sendmail &&
+	rm -fr outdir &&
+	git format-patch --cover-letter -2 -o outdir &&
+	test_must_fail git send-email \
+	  --from="Example <nobody@example.com>" \
+	  --to=nobody@example.com \
+	  --smtp-server="$(pwd)/fake.sendmail" \
+	  outdir/0002-*.patch \
+	  outdir/0000-*.patch \
+	  outdir/0001-*.patch \
+	  2>errors >out &&
+	grep "SUBJECT HERE" errors &&
+	test -z "$(ls msgtxt*)"
+'
+
+test_expect_success '--force sends cover letter template anyway' '
+	clean_fake_sendmail &&
+	rm -fr outdir &&
+	git format-patch --cover-letter -2 -o outdir &&
+	git send-email \
+	  --force \
+	  --from="Example <nobody@example.com>" \
+	  --to=nobody@example.com \
+	  --smtp-server="$(pwd)/fake.sendmail" \
+	  outdir/0002-*.patch \
+	  outdir/0000-*.patch \
+	  outdir/0001-*.patch \
+	  2>errors >out &&
+	! grep "SUBJECT HERE" errors &&
+	test -n "$(ls msgtxt*)"
+'
+
 test_done