I was looking at my rails app's disk usage today and noticed that my vendored version of devise 2.0.0 was using over 13 megabytes of disk space!
Digging in, I discovered:
is the culprit.
Doing a fresh gem install into an empty gemset confirmed it.
This file doesn't appear in the git repo, so it's probably getting generated as part of the gem build process prior to hosting on rubygems.org.
Fix gemspec to not include tmp or log files, closes #1632.