The code below is from BTreeScan.delete(). If the call to reposition() manages to position on the row, an exception is raised indicating that the row could not be found. If the row is not found, no exception is raised, but code later in the method will probably throw a NullPointerException because scan_position.current_leaf is set to null by reposition(). I believe that "if (reposition(...))" should be changed to "if (!reposition(...))". According to the test coverage reports, this code is not exercised by any of the existing tests.
// lost latch on page in order to wait for row lock.
// Because we have scan lock on page, we need only
// call reposition() which will use the saved record
// handle to reposition to the same spot on the page.
// We don't have to search the
// tree again, as we have the a scan lock on the page
// which means the current_rh is valid to reposition on.
if (reposition(scan_position, false))