Race condition; reading, logging

[laldoroty]

No description provided.

[wmwv]

1. Can you be more specific about the original problem?
2. Please add a test that demonstrates the problem and that these changes fix it.

[wmwv]

Is the following snippet of text the thing that this PR is fixing?

           # NOTE -- we were getting weird race condition issues where sometimes
             #   the FITS header reading failed.  We aren't sure exactly what's going
             #   on, but the hypothesis is bad filesystem behavior.  The earlier
             #   writefits returns, but somehow the file wasn't really fully written
             #   to either disk, or to the memory buffers that the fits.getheader
             #   here read.  Put in an ugly hack of retring and sleeping to work
             #   around this.