PXC correctly conflicts with 5.0, 5.1 and 5.5, but it doesn't conflict against 5.6.
Since the rule is 5.x ignores 5.y and 5.y conflicts 5.x if x < y, we've got a little bit of an assimetry here -- either can conlict with the other.
Let's choose PXC to conflict against 5.6 and have 5.6 ignore PXC, this way considering PXC as a "latter product" than any Percona Server version.
PXC correctly conflicts with 5.0, 5.1 and 5.5, but it doesn't conflict against 5.6.
Since the rule is 5.x ignores 5.y and 5.y conflicts 5.x if x < y, we've got a little bit of an assimetry here -- either can conlict with the other.
Let's choose PXC to conflict against 5.6 and have 5.6 ignore PXC, this way considering PXC as a "latter product" than any Percona Server version.