ticket:10 some dup detection rework

Old code works for me but fails on barista
ticket:10 more hacks

try to use atomic transaction to fix dup failures on getbarista
ticket:10 model = type(instance) instead of sender
ticket:10 more workarounds
ticket:10 add some debugging

to see what's happens on test
ticket:10 try to fix dups
Merge branch 't10_signal'