Simple docker run hiveio/hive --help fails

gandalf@grey:~$ docker run hiveio/hive:v-develop --help
setting user hived uid to value 1000
+ '[' -n '' ']'
Shared memory file directory (SHM_DIR) /home/hived/datadir/blockchain does not exist. Exiting.

It fails when SHM_DIR is not overridden, because the default one points to a dir that doesn't exist yet.