commit: accept "scissors" with CR/LF line endings

This change enhances `git commit --cleanup=scissors` by detecting
scissors lines ending in either LF (UNIX-style) or CR/LF (DOS-style).

Regression tests are included to specifically test for trailing
comments after a CR/LF-terminated scissors line.

Signed-off-by: Luke Bonanomi <lbonanomi@gmail.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

t/t7502-commit-porcelain.sh

@@ -586,6 +586,48 @@ test_expect_success 'cleanup commit messages (scissors option,-F,-e, scissors on
 	test_must_be_empty actual
 '
 
+test_expect_success 'helper-editor' '
+
+	write_script lf-to-crlf.sh <<-\EOF
+	sed "s/\$/Q/" <"$1" | tr Q "\\015" >"$1".new &&
+	mv -f "$1".new "$1"
+	EOF
+'
+
+test_expect_success 'cleanup commit messages (scissors option,-F,-e, CR/LF line endings)' '
+
+	test_config core.editor "\"$PWD/lf-to-crlf.sh\"" &&
+	scissors="# ------------------------ >8 ------------------------" &&
+
+	test_write_lines >text \
+	"# Keep this comment" "" " $scissors" \
+	"# Keep this comment, too" "$scissors" \
+	"# Remove this comment" "$scissors" \
+	"Remove this comment, too" &&
+
+	test_write_lines >expect \
+	"# Keep this comment" "" " $scissors" \
+	"# Keep this comment, too" &&
+
+	git commit --cleanup=scissors -e -F text --allow-empty &&
+	git cat-file -p HEAD >raw &&
+	sed -e "1,/^\$/d" raw >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'cleanup commit messages (scissors option,-F,-e, scissors on first line, CR/LF line endings)' '
+
+	scissors="# ------------------------ >8 ------------------------" &&
+	test_write_lines >text \
+	"$scissors" \
+	"# Remove this comment and any following lines" &&
+	cp text /tmp/test2-text &&
+	git commit --cleanup=scissors -e -F text --allow-empty --allow-empty-message &&
+	git cat-file -p HEAD >raw &&
+	sed -e "1,/^\$/d" raw >actual &&
+	test_must_be_empty actual
+'
+
 test_expect_success 'cleanup commit messages (strip option,-F)' '
 
 	echo >>negative &&

wt-status.c

@@ -22,7 +22,7 @@
 #define AB_DELAY_WARNING_IN_MS (2 * 1000)
 
 static const char cut_line[] =
-"------------------------ >8 ------------------------\n";
+"------------------------ >8 ------------------------";
 
 static char default_wt_status_colors[][COLOR_MAXLEN] = {
 	GIT_COLOR_NORMAL, /* WT_STATUS_HEADER */
@@ -1068,15 +1068,22 @@ conclude:
 	status_printf_ln(s, GIT_COLOR_NORMAL, "%s", "");
 }
 
+static inline int starts_with_newline(const char *p)
+{
+    return *p == '\n' || (*p == '\r' && p[1] == '\n');
+}
+
 size_t wt_status_locate_end(const char *s, size_t len)
 {
 	const char *p;
 	struct strbuf pattern = STRBUF_INIT;
 
 	strbuf_addf(&pattern, "\n%c %s", comment_line_char, cut_line);
-	if (starts_with(s, pattern.buf + 1))
+	if (starts_with(s, pattern.buf + 1) &&
+	    starts_with_newline(s + pattern.len - 1))
 		len = 0;
-	else if ((p = strstr(s, pattern.buf)))
+	else if ((p = strstr(s, pattern.buf)) &&
+		 starts_with_newline(p + pattern.len))
 		len = p - s + 1;
 	strbuf_release(&pattern);
 	return len;