Tell git about the changed files specifically.

misc/python3/depgraph.sh

@@ -20,12 +20,11 @@ if git diff-index --quiet HEAD; then
   exit 0
 fi
 
-# Commit everything that changed.  It should be tahoe-deps.json and
-# tahoe-ported.json.
 git config user.name 'Build Automation'
 git config user.email 'tahoe-dev@tahoe-lafs.org'
 
-git commit -am "\
+git add tahoe-deps.json tahoe-ported.json.
+git commit -m "\
 Built from ${CIRCLE_REPOSITORY_URL}@${CIRCLE_SHA1}
 
 tahoe-depgraph was $(git rev-parse HEAD)