ZODB Components: Dead lock on ImportLock (WORKAROUND).

ImportLock is acquired when synchronizeDynamicModules() and also when calling
find_module() for Components. Then, if an object has to be loaded during
migration to Portal Type Class, it fails because the main thread acquired the
ImportLock() needed by the other thread pulling the object from ZEO and trying
to acquired ImportLock() as a side-effect.