fixup! built-in add -p: implement the hunk splitting feature

When counting how many lines a hunk can be split into, we need to be
careful to take line comments in the diff into account, i.e. lines
starting with a backslash. Example:

	[...]
	-}
	\ No newline at end of file
	+}

Logically, these line comments belong to the line preceding them,
therefore we need to pretend that they have the same diff marker (space,
minus or plus character).

This fixes #2364.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

add-patch.c

@@ -511,10 +511,9 @@ static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
 			    (int)(eol - (plain->buf + file_diff->head.start)),
 			    plain->buf + file_diff->head.start);
 
-		if ((marker == '-' || marker == '+') &&
-		    (*p == ' ' || *p == '\\'))
+		if ((marker == '-' || marker == '+') && *p == ' ')
 			hunk->splittable_into++;
-		if (marker)
+		if (marker && *p != '\\')
 			marker = *p;
 
 		p = eol == pend ? pend : eol + 1;

t/t3701-add-interactive.sh

@@ -472,6 +472,18 @@ test_expect_failure 'split hunk "add -p (no, yes, edit)"' '
 	! grep "^+31" actual
 '
 
+test_expect_success 'split hunk with incomplete line at end' '
+	git reset --hard &&
+	printf "missing LF" >>test &&
+	git add test &&
+	test_write_lines before 10 20 30 40 50 60 70 >test &&
+	git grep --cached missing &&
+	test_write_lines s n y q | git add -p &&
+	test_must_fail git grep --cached missing &&
+	git grep before &&
+	test_must_fail git grep --cached before
+'
+
 test_expect_failure 'edit, adding lines to the first hunk' '
 	test_write_lines 10 11 20 30 40 50 51 60 >test &&
 	git reset &&