t7810-grep.sh: fix duplicated test name

diff --git a/builtin/diff-index.c b/builtin/diff-index.c
index ce15b23042d8472573b88e0ee9a6032673321ea3..d979824f9395a0cbc8ffffa9cede524589710d43 100644 (file)
--- a/builtin/diff-index.c
+++ b/builtin/diff-index.c
@@ -7,7 +7,7 @@
 
 static const char diff_cache_usage[] =
 "git diff-index [-m] [--cached] "
-"[<common diff options>] <tree-ish> [<path>...]"
+"[<common-diff-options>] <tree-ish> [<path>...]"
 COMMON_DIFF_OPTIONS_HELP;
 
 int cmd_diff_index(int argc, const char **argv, const char *prefix)