Bugfix: stop if directory already exists

Fix a typo: We do not want to run the directory as command,
and want to terminate if the directory exists
Additionally, update the usage message

Signed-off-by: Josef Weidendorfer <Josef.Weidendorfer@gmx.de>
Signed-off-by: Junio C Hamano <junkio@cox.net>

git-clone.sh

@@ -9,7 +9,7 @@
 unset CDPATH
 
 usage() {
-	echo >&2 "* git clone [-l [-s]] [-q] [-u <upload-pack>] [-n] <repo> <dir>"
+	echo >&2 "* git clone [-l [-s]] [-q] [-u <upload-pack>] [-n] <repo> [<dir>]"
 	exit 1
 }
 
@@ -98,7 +98,7 @@ fi
 dir="$2"
 # Try using "humanish" part of source repo if user didn't specify one
 [ -z "$dir" ] && dir=$(echo "$repo" | sed -e 's|/$||' -e 's|:*/*\.git$||' -e 's|.*/||g')
-[ -e "$dir" ] && $(echo "$dir already exists."; usage)
+[ -e "$dir" ] && echo "$dir already exists." && usage
 mkdir -p "$dir" &&
 D=$(
 	(cd "$dir" && git-init-db && pwd)