p4verify.sh P4D_VERSION unbound variable w/'-o MISSING' and env not sourced.
An error indicating 'P4D_VERSION: unbound variable' is displayed if
p4verify.sh is called without the SDP environment having been sourced
first, e.g. with p4_vars being sourced in ~perforce/.bashrc, or if
p4verify.sh is called with 'p4master_run' or 'run_if_{master|replica|edge}'
as all such scripts source p4_vars before calling scripts.
The workaround is to source p4_vars one way or an another.
A proper fix is a code change to source p4_vars before P4D_VERSION is
checked.