grep disambiguate errors
'
+test_expect_success 'feed two files' '
+ rm -fr outdir &&
+ git format-patch -2 -o outdir &&
+ GIT_SEND_EMAIL_NOTTY=1 git send-email \
+ --dry-run \
+ --from="Example <nobody@example.com>" \
+ --to=nobody@example.com \
+ outdir/000?-*.patch 2>errors >out &&
+ grep "^Subject: " out >subjects &&
+ test "z$(sed -n -e 1p subjects)" = "zSubject: [PATCH 1/2] Second." &&
+ test "z$(sed -n -e 2p subjects)" = "zSubject: [PATCH 2/2] add master"
+'
+
test_done