It is common knowledge that one does not need to reboot for updates to take effect in GNU Linux.
However, in actual practice, this is not so. I could cite many examples, but this should suffice:
On Sunday evening, I installed a new updates-testing version of mesa and then I suspended the machine for the night. The following Monday morning (yesterday), I resumed the machine and suspended it again around noon. I again resumed the machine at about suppertime and _powered_ _it_ _down_ about 2 hours later. An hour or two after that, I powered it back up and the mesa testing update turned out to be bad and I was not able to log in. I did not know which program was at fault, because the bad program had been installed over 24 hours prior, but was only showing itself to be bad after a power off.
Could someone explain how reboots are not needed in Linux for updates to _take_, given the evidence to the contrary.