Automatic sanity-testing: PASSED, see http://jenkins.bluematt.me/pull-tester/e83a90f127060487b7a6717a740a59db244b4e53 for binaries and test log.
This test script verifies pulls every time they are updated. It, however, dies sometimes and fails to test properly. If you are waiting on a test, please check timestamps to verify that the test.log is moving at http://jenkins.bluematt.me/pull-tester/current/
Contact BlueMatt on freenode if something looks broken.

Did my hint draw your attention on this? Nice finde anyway :).

@Diapolo, yes, and that it was not the diskspace warning but a leveldb error (likely in the network thread while accepting a block). It's still strange that it sometimes worked (like for askFee) and sometimes did not, but this should solve it for good.