Always check if there's a new xbps package version available
while *installing* or *updating* in any form.
This fixes the following scenario:
- xbps-0.53_10 is currently installed
- xbps-0.54_1 is available in repo
- xbps-install --update netbsd-wtf || xbps-install new-pkg || xbps-install --update
As expected any of the following scenarios in last cmd will use *this*
transaction to autoupdate xbps and its reverse dependencies.
Another transaction will be necessary to install or update the other unrelated
packages.
Added a new test case to verify this case and improve the other test
cases with more extensive checks.
b672e1a7f2