builtin/fetch.c: use error_errno()

A couple of newlines are also removed, because both error() and
error_errno() automatically append a newline.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/builtin/fetch.c b/builtin/fetch.c
index e4639d8..4227a40 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -607,7 +607,7 @@
 
 	fp = fopen(filename, "a");
 	if (!fp)
-		return error(_("cannot open %s: %s\n"), filename, strerror(errno));
+		return error_errno(_("cannot open %s"), filename);
 
 	if (raw_url)
 		url = transport_anonymize_url(raw_url);
@@ -848,7 +848,7 @@
 	FILE *fp = fopen_for_writing(filename);
 
 	if (!fp)
-		return error(_("cannot open %s: %s\n"), filename, strerror(errno));
+		return error_errno(_("cannot open %s"), filename);
 	fclose(fp);
 	return 0;
 }