[PATCH] completion: avoid config variable name lookup error in nounset mode

Config variable name lookup accesses the `sfx` variable before it has
been set, causing an error in "nounset" mode. Initialize to an empty
string to avoid that.

    $ git config submodule.<Tab>bash: sfx: unbound variable

Signed-off-by: Ville Skyttä <redacted>
---
 contrib/completion/git-completion.bash | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index 4bdd27ddc8..ecc9352755 100644
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash

@@ -2631,7 +2631,7 @@ __git_complete_config_variable_value ()
 #                 subsections) instead of the default space.
 __git_complete_config_variable_name ()
 {
-	local cur_="$cur" sfx
+	local cur_="$cur" sfx=""
 
 	while test $# != 0; do
 		case "$1" in

-- 
2.25.1