[CentOS] futex hang workaround by rebooting first (?)

The previously noted upgrade-to-4.4 recipe:

yum update yum sqlite python-sqlite ; yum update

worked more consistently than running "yum upgrade," but it too fell victim
to the futex hang.

In my limited testing, a reboot of the machine before starting the upgrade
gave me a 100% success rate.

Given two identical machines, one that had been used for a few days and 
one that was freshly rebooted, the former would exhibit a futex hang, 
while the latter updated just fine.

Cheers,
Zube