Otherwise old apkovl:s can fail to boot, and are hard to fix.

(from redmine: issue id 50, created on 2009-06-23, closed on 2009-07-28)

• Changesets:
  • Revision 1531192c by Timo Teräs on 2009-07-07T07:03:30Z:

add: ignore install failures on 'apk add --force'

and use this option in initramfs, so we are likely to get an usable
environment even if some packages from world are missing. fixes #50.