diffcore-pickaxe: respect --no-textconv

git log -S doesn't respect --no-textconv:

    $ echo '*.txt diff=wrong' > .gitattributes
    $ git -c diff.wrong.textconv='xxx' log --no-textconv -Sfoo
    error: cannot run xxx: No such file or directory
    fatal: unable to read files to diff

Reported-by: Matthieu Moy <Matthieu.Moy@grenoble-inp.fr>
Signed-off-by: Simon Ruderich <simon@ruderich.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diffcore-pickaxe.c

@@ -86,8 +86,10 @@ static int diff_grep(struct diff_filepair *p, struct diff_options *o,
 	if (diff_unmodified_pair(p))
 		return 0;
 
+	if (DIFF_OPT_TST(o, ALLOW_TEXTCONV)) {
 		textconv_one = get_textconv(p->one);
 		textconv_two = get_textconv(p->two);
+	}
 
 	mf1.size = fill_textconv(textconv_one, p->one, &mf1.ptr);
 	mf2.size = fill_textconv(textconv_two, p->two, &mf2.ptr);
@@ -201,8 +203,10 @@ static int has_changes(struct diff_filepair *p, struct diff_options *o,
 	if (!o->pickaxe[0])
 		return 0;
 
+	if (DIFF_OPT_TST(o, ALLOW_TEXTCONV)) {
 		textconv_one = get_textconv(p->one);
 		textconv_two = get_textconv(p->two);
+	}
 
 	/*
 	 * If we have an unmodified pair, we know that the count will be the

t/t4209-log-pickaxe.sh

@@ -80,6 +80,20 @@ test_expect_success 'log -G -i (match)' '
 	test_cmp expect actual
 '
 
+test_expect_success 'log -G --textconv (missing textconv tool)' '
+	echo "* diff=test" >.gitattributes &&
+	test_must_fail git -c diff.test.textconv=missing log -Gfoo &&
+	rm .gitattributes
+'
+
+test_expect_success 'log -G --no-textconv (missing textconv tool)' '
+	echo "* diff=test" >.gitattributes &&
+	git -c diff.test.textconv=missing log -Gfoo --no-textconv >actual &&
+	>expect &&
+	test_cmp expect actual &&
+	rm .gitattributes
+'
+
 test_expect_success 'log -S (nomatch)' '
 	git log -Spicked --format=%H >actual &&
 	>expect &&
@@ -116,4 +130,18 @@ test_expect_success 'log -S -i (nomatch)' '
 	test_cmp expect actual
 '
 
+test_expect_success 'log -S --textconv (missing textconv tool)' '
+	echo "* diff=test" >.gitattributes &&
+	test_must_fail git -c diff.test.textconv=missing log -Sfoo &&
+	rm .gitattributes
+'
+
+test_expect_success 'log -S --no-textconv (missing textconv tool)' '
+	echo "* diff=test" >.gitattributes &&
+	git -c diff.test.textconv=missing log -Sfoo --no-textconv >actual &&
+	>expect &&
+	test_cmp expect actual &&
+	rm .gitattributes
+'
+
 test_done