Commit ed258c751b (change
datestamp->timestamp) broke a lot of builders. The symlinks
and upload logic were all based on the datestamp. Update it
to use the new timestamp format.
Commit b7e493b4e4 (run trigger_post_build
after every successful spec) broke a lot of builders. The configs were
written to be called only after everything was done, but by calling it
after the first build (stage1 only), all the other artifacts we expected
did not yet exist.
Change post_build to pass the current set & spec name down so the config
can figure out what is available at that point in time.
