Kludge to fix race condition

On some Android devices, clicking through OPDS catalogs, a large
percentage of the time you will get the emptyCatalog message ("Catalog
is empty, sorry").  On clicking reload you will usually get the catalog
loaded correctly.

This seems due to some kind of problem with how mutual exclusion is
done.  It seems there is some kind of race condition.

This is a bad problem and has been around for months, at least.  It is a
big problem - sometimes new users will click OPDS and see nothing, not
know to click reload and give up.  Even for users who know to click
reload it can be annoying to continually click reload.

This fix is kludgey but its behavior seems to be better than the
existing behavior.  One question is, how long does this commit delay the
load of a long loading normal sized catalog load?  Another question is,
how does it deal with very large catalog pages?  In both cases I believe
the behavior of this commit is better than its predecessor.

This commit is definitely kludgey and I'm sure a more elegant fix can be
done, but this fix is all I have time for at the moment.