munge-0.5.13 adds support for getrandom() (which was added to glibc in v2.25). munged calls getrandom() once during its initialization. getrandom() will block until its entropy pool has been initialized, after which it never blocks for reads of up to 256 bytes.
You mention that you're running in a VM under VMware. I've had VMs in the past that were starved for entropy at boot (unrelated to MUNGE). I addressed that by installing haveged. -Chris
