git: browsing paths with spaces when using the start command

msysGit issue 258 tracks a problem opening a browser onto file
paths that contain spaces or parentheses when calling the
web--browse script. This patch modifies how the start command is
called to solve this.
Signed-off-by: NPat Thoyts <patthoyts@users.sourceforge.net>
Signed-off-by: NSteffen Prohaska <prohaska@zib.de>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

git-web--browse.sh

@@ -161,9 +161,12 @@ case "$browser" in
 		;;
 	esac
 	;;
-    w3m|links|lynx|open|start)
+    w3m|links|lynx|open)
 	eval "$browser_path" "$@"
 	;;
+    start)
+        exec "$browser_path" '"web-browse"' "$@"
+        ;;
     dillo)
 	"$browser_path" "$@" &
 	;;