completion: bash: fix for multiple dash commands

Otherwise options of commands like 'for-each-ref' are not completed.

Tested-by: David Aguilar <[email protected]>
Signed-off-by: Felipe Contreras <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: felipec

contrib/completion/git-completion.bash

@@ -421,7 +421,7 @@ __gitcomp_builtin ()
 	local incl="${2-}"
 	local excl="${3-}"
 
-	local var=__gitcomp_builtin_"${cmd/-/_}"
+	local var=__gitcomp_builtin_"${cmd//-/_}"
 	local options
 	eval "options=\${$var-}"