my_seek: Assertion `fd != -1' failed"

In difficult optimize/repair situations the server could crash.
Under some circumstances the server retries an optimize/repair
with more elaborate options. But it did not check if the first
attempt failed so badly that a second one must not be tried.

This could happen when a new data file has been created
but it was not possible to open it. In this case the
repair leaves behind a table with closed data file.
This must not be used for another repair attempt.

We do now detect the closed data file and do not try
another repair attempt in this situation.

No test case. The required table corruption can not be
repeated easily. There is a test program attached to
bug 25433.


sql/ha_myisam.cc:
  Bug#25289 - repair table causes "my_seek.c:56:
              my_seek: Assertion `fd != -1' failed"
  Added code to detect a closed data file. It could be closed
  by a preceeding repair attempt. We must not try another
  repair then.