completion: add git config credentialCache.ignoreSIGHUP

Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/completion/git-completion.bash

@@ -2455,6 +2455,7 @@ _git_config ()
 		credential.helper
 		credential.useHttpPath
 		credential.username
+		credentialCache.ignoreSIGHUP
 		diff.autorefreshindex
 		diff.external
 		diff.ignoreSubmodules