[yocto] What keeps sstate from being used?

[Gary Thomas]

I just had a [nearly] complete build failed (building webkitgtk
after some 6000 tasks).  I decided to try the 'rebuild from sstate'
by removing my 'tmp' directory and rebuild.  Bitbake proceeded to
run 2200 setscene tasks and then [it seems] started over on the
build, rebuilding the target gcc, the kernel, who knows what else...
These are all things that I thought had been completed before
during the initial ~6000 steps.

What could be going on and why couldn't it just pick up using
sstate from where it left off?

-- 
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Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
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