[mythtv] Mythvideo and updating metadata

[BP]

With the additional artwork displayed in MythVideo I have been updating 
my metadata.  This has lead me to one very big annoyance:  MythVideo 
deletes metadata even when the tmdb query returns no data.  This has 
been for various reasons such as network errors, backend errors at tmdb 
(rails errors), not very robust searching of tmdb (there are several 
movies the tmdb script returns nothing for which I can find searching 
directly at the site and which imdb.pl previously found) and movies not 
having any data on tmdb.

Considering there is an option to "reset metadata", should the "download 
metadata" and "download images only" features reset fields when no data 
is found?  My preference is to only update fields that data was found 
for.  I definitely don't think that data should be reset to defaults 
when an error searching was encountered.

If others agree with my perspective and if someone wants to point me to 
the code involved, I'm willing to work on a patch.