Bail out immediately instead of redownloading .idx
Bail out immediately instead of redownloading .idx

This should make diagnosing / fixing corrupted bloom filters and midx
files easier, and is generally more sane behavior.

Signed-off-by: Brandon Low <a52c3838af000af4c7c0bc518c135eded66d273a@lostlogicx.com>

pombredanne/bup,mhoeher/bup,pombredanne/bup,mhoeher/bup,gevaerts/bup,gevaerts/bup,ToxicFrog/bup,gevaerts/bup,ToxicFrog/bup,apenwarr/bup,apenwarr/bup,tjanez/bup,ToxicFrog/bup,tjanez/bup,jbaber/bup,apenwarr/bup,pombredanne/bup,jbaber/bup,jbaber/bup,ToxicFrog/bup,jbaber/bup,mhoeher/bup,tjanez/bup,mhoeher/bup,tjanez/bup,jbaber/bup,tjanez/bup,ToxicFrog/bup,pombredanne/bup,apenwarr/bup,mhoeher/bup,mhoeher/bup,pombredanne/bup,jbaber/bup,tjanez/bup,gevaerts/bup,gevaerts/bup,pombredanne/bup