We identified a pretty major regression in 2.5.11, and wanted to quickly get a follow-up release out for you. Some changes to our repository communication code resulted in a crash when forming a HTTP header used for several hosting services. This has been fixed, and things should work well once again.
We've also fixed an issue that could occur when sending e-mails for review requests that modify large numbers of files. We send a X-ReviewBoard-Diff-For header that lists the files, for filtering purposes, but some e-mail servers had issues with the length of this header. We've now capped this to ensure e-mails are sent reliably.
It's a small release, but the release notes are available.
If you missed it, check out the 2.5.11 release notes for all the performance improvements, bug fixes, and features we shipped last night.