Title: #905: ipapython/graph.py complexity optimization.
I've just read the code and I saw that graph bfs uses not optimal
for Python solution. So I've edited it with more optimal one.
Also I've changed string formatting for Value Errors raise and
deletion of edges in remove_vertex method because there's no need
to store redundant variable in memory.
Could you please take a look and leave some comments and maybe
To pull the PR as Git branch:
git remote add ghfreeipa https://github.com/freeipa/freeipa
git fetch ghfreeipa pull/905/head:pr905
git checkout pr905