[AstroPy] Capturing pyfits warnings

[Phil Hodge]

> Why would that be the case?  

> What is the preferred behavior?


If the problem was in fact that the file size was not an integral 
multiple of 2880, but the contents were not actually corrupted, one 
could copy the file to another and correct the problem simply by opening 
the file with pyfits and then using the writeto method.  If you can't 
open the file with pyfits, you can't fix the problem using pyfits.

Phil