hi oleg,
that is not necessarily a bug, depending on whether the astrometric solution in the header matches the field orientation or not.
i don't have such images at hand. am i correct that the chip in question is number 1?
in that case, you could edit
process_split_CFH12K@CFHT99.sh, locate the line saying
-M11 "-1,-1,-1,-1,-1,-1,-1,-1,1,-1,-1,-1"
and change -1 to +1 for the first element, i.e.
-M11 "1,-1,-1,-1..."
however, i am afraid that this might screw up the reference pixels and other stuff.
i have never worked with data from that instrument and just adopted the configurations from other people.
the CCD and header configurations of CFH12K changed about a dozen of times during its history, so you are in for a lot of trouble.
if you have problems with astrometry, i suggest you run scamp first with "mosaic_type = loose" until you have a good solution. once that is done, "update header", re-create the catalogs, and try with the normal scamp mosaic configuration.
mischa