[PATCH v1] convert: fix return value for apply_multi_file_filter() on SIGPIPE

If a pipe write fails and errno is set to EPIPE then we execute the
"error" path. However, as "err" can still be 0 the return value of
apply_multi_file_filter() would indicate success.

Fix this by setting "err" to the value of "errno" in case of a pipe
write failure.

Noticed-by: Ben Peart [off-list ref]
Signed-off-by: Lars Schneider <redacted>
---

Notes:
    Base Ref: master
    Web-Diff: https://github.com/larsxschneider/git/commit/41a217c246
    Checkout: git fetch https://github.com/larsxschneider/git errno-check-v1 && git checkout 41a217c246

 convert.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/convert.c b/convert.c
index 8d652bf27c..586e0cdd45 100644
--- a/convert.c
+++ b/convert.c

@@ -753,6 +753,7 @@ static int apply_multi_file_filter(const char *path, const char *src, size_t len
 	sigchain_pop(SIGPIPE);
 
 	if (err || errno == EPIPE) {
+		err = err ? err : errno;
 		if (!strcmp(filter_status.buf, "error")) {
 			/* The filter signaled a problem with the file. */
 		} else if (!strcmp(filter_status.buf, "abort")) {

base-commit: b14f27f91770e0f99f64135348977a0ce1c7993a
-- 
2.12.2