Every time I hit "Create Patch" on issue 11816 for my get_opinfo branch, I get the error message: "9512712044a6.diff is already available"

It first started happening when I hit 'Create Patch' after unlinking the previous diff (which used the filename that Roundup is apparently trying to reuse). However, relinking that file didn't make the problem go away.

OK, the problem really is that it keeps trying to diff against the same changeset, ignoring all subsequent commits to that branch:
https://bitbucket.org/ncoghlan/cpython_sandbox/changesets/9512712044a6

AFAICT, 9512712044a6 *is* the most recent change on the get_opinfo branch.

Which changeset do you think should it have used instead?

Any of the changesets that appear above it here: https://bitbucket.org/ncoghlan/cpython_sandbox/changesets/tip/branch%28%22get_opinfo%22%29

There have been at least 4 meaningful updates since then, and 7 more recent merges from default.

The current latest changeset on that branch is this merge from default: https://bitbucket.org/ncoghlan/cpython_sandbox/changeset/5ce60675e572

> The current latest changeset on that branch is this merge from default: https://bitbucket.org/ncoghlan/cpython_sandbox/changeset/5ce60675e572

The repository you specified on issue 11816 is
http://hg.python.org/sandbox/ncoghlan, not
https://bitbucket.org/ncoghlan/cpython_sandbox.
In that repository, those changes (including 5ce60675e572) do not
exist.

Ah, you're right - I added it before I moved my sandbox over to BitBucket, and then my brain was doing the "fill in what you expect to see rather than reading what is actually there" trick.

Sorry for the noise.