When there's a new xbps update, xbps-install(1) will now return
EBUSY (16) and a message (if dry-run disabled) explaining
how to proceed.
If there's an update and transaction does not contain xbps, it will
error out unless the 'xbps' pkg is the only target pkg, i.e:
# xbps-install -Su
# echo $?
16
To update xbps, the only way to proceed is to explicitly declare
it as an update, i.e:
# xbps-install -u xbps
The dry-run mode will still show there's an xbps update.
Modified the existing test cases to satisfy the new behaviour.
Closes#166Closes#142
166caab986