The 'grep' logic of Change-Id I58f3f4a26ad6fa4698d87475cefb6ab21e66b15a
seems to be inverted. if "overlay2" is found (grep successful) the
exit code of grep is '0'.
Change-Id: I334b0c71ef626ffd2c84097e902a5164faa3fa8b
Related: OS#5827
It's really annoying that OBS uses Debian_8.0 and Debian_9.0 (for 8.x
and 9.x) and then Debian_10 for 10.x. Let's work around this by some
conditional vars_file trickery, hopefully once and for all.
Change-Id: I45c4752774f44332b3f9aaf875f49043c03ec5ca