Add fingerprint for bug 1368910

Bug 1368910 is triggered due to failure to access a external site (for
interpshinx) combined with causing docs jobs to fail on warnings. Since
there isn't a single line that shows us both limit the query to
nova-docs since we know that is fails on warnings.

Change-Id: I59bd182e64e46729446b89d5f4b8d492fd37eae8
Related-Bug: #1368910
Merge "Add fingerprint for bug 1368910"