As part of the sharded test suite being added for the FCV upgrade/downgrade project, there is a failure to create a database with 'operation was interrupted' error. Looking at the log, it seems we attempt to abort an internal txn when the fcv downgrade command is received, but we can't find the txn in question:
"Unable to abort internal transaction","attr":
{
reason: "NoSuchTransaction: Transaction with

has been aborted."...
This happened in several cases:
https://parsley.mongodb.com/resmoke/adaafb25f3c051dbeadc18fc1cf6e2c3/test/1764e1cc8fb4fb64fa1c0967d7e4f127?bookmarks=0,71,104,111,133,136,841&shareLine=111

also: https://parsley.mongodb.com/resmoke/c714af65f0168ccef874ff70d13425a3/test/1764e1c69f9e9aa04d5f30dee4d2e15e?bookmarks=0,57&shareLine=0