Enable/disable/enable of Epoch may corrupt repository
In a repository in which Epoch GC is enabled, if epoch is later disabled
by editing the using the configuration file to set STN_EPOCH_GC_ENABLED
= FALSE, then later epoch is renabled, this may result in repository corruption.
The internal bitmap that records Epoch GC OOPs was not cleared correctly
when Epoch is disabled via the modifying the configuration file setting.
When Epoch GC is later run, after being re-enabled, it will use this out
of date information and OOPs may be reclaimed a second time.
Prior to turning Epoch GC on, manually clears the internal structures by