POSKeyError during commit after savepoint rollback

[gotcha]

When a BTree is added and modified in a savepoint before this savepoint is rolled back, consecutive transaction commit fails with a POSKeyError.

This is triggered in certain cases in Plone 3 to 4 migration.

See also http://rpatterson.net/blog/poskeyerror-during-commit

[jimfulton]

Is something actually calling readCurrent?

[gotcha]

readCurrent is called via adding a key value pair to a BTree.

line 346 of the test in the pull request tries to document that fact

[gotcha]

Is there anything avoiding to merge pull request #19 ?

[jimfulton]

Nope, just me letting it fall through the cracks. Merged. Thanks!