Tim, All,
I have completed downgrading through the sets of binaries I have and from that I can summize that this bug was introduced sometime between 3/29 and 4/10. In my 3/29 build, kwrite is fine. In my 4/10 build, this bug effects kwrite, kate, all editors EXCEPT kedit. In kedit, I can continue to paste away without any crash (I'm sure it makes no use of katepart...)
So that is the best I can do in narrowing it down rapidly from existing binaries I have.
Darrell, do you have any binaries between 3/29 and 4/10 that could help narrow? There were a ton of changes that went into the GIT tree for tdelibs and tdebase during that two week period. It would be great if we could further narrow it by simply loading binaries rather going through all the commits...
I've updated 979 with the info.