Update dpranke's entry in the WATCHLISTS.

TBR=iannucci@chromium.org
BUG=

Review URL: https://codereview.chromium.org/848133002

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@293621 0039d316-1c4b-4281-b951-d872f2087c98

WATCHLISTS

@@ -20,7 +20,7 @@
     'this_file': [],
     'depot_tools': [
       'cmp-cc@chromium.org',
-      'dpranke@chromium.org',
+      'dpranke+depot_tools@chromium.org',
       'iannucci+depot_tools@chromium.org',
     ],
   },