abuild-rootbld missing runtime dependency

Looks like envsubst is mandatory, is it?

$ abuild rootbld 
...                                                                                                                                                                           
/usr/bin/abuild: line 2420: envsubst: not found                                                                                                                                                                    
...

$ apk policy abuild-rootbld
abuild-rootbld policy:
  3.9.0-r1:
    lib/apk/db/installed
    etc/apk/cache
    http://nl.alpinelinux.org/alpine/edge/main