[OE-core] Cache unihash ... doesn't match BB_UNIHASH ...

[Alex Kiernan]

Hi

We've got a couple of multiconfig builds with different configurations
in one bitbake run (whether it needs to be like this a different
question - I suspect we had something that worked and stopped there!)

However, for sometime we've been seeing errors like this on master
(the recipes vary):

ERROR: mc:forensic:ca-certificates-20190110-r0
do_deploy_source_date_epoch: Cache unihash
37d2546973a2b7c16fbcb1a8dd4939e4a1bba8c3d6d2dfb6e7204ca08d437ace
doesn't match BB_UNIHASH
09baf78bd9316acdd308980c42ea4ed1eacea61bcc0d840c36293d1a5a22db69

Coupled with deadlock messages:

WARNING: Runqeueue deadlocked on deferred tasks, forcing task
mc:factory:virtual:native:/var/lib/jenkins/workspace/nanohub_master/build/../poky/meta/recipes-support/sqlite/sqlite3_3.31.1.bb:do_populate_sysroot

Any pointers to whereabouts I should be looking for what we've got wrong?

-- 
Alex Kiernan