pg11b1 from outside a txn: "VACUUM cannot run inside a transaction block": should be: ...or multi-command string

in pg10:

ts=# begin;VACUUM FULL pg_toast.pg_toast_2619;
BEGIN
ERROR: 25001: VACUUM cannot run inside a transaction block
LOCATION: PreventTransactionChain, xact.c:3167
=> sounds fine

$ psql postgres -c 'SELECT 1; VACUUM pg_statistic'
ERROR: VACUUM cannot be executed from a function or multi-command string
=> sounds fine

In pg11b1:

pryzbyj=# begin;VACUUM FULL pg_toast.pg_toast_2619;
BEGIN
ERROR: 25001: VACUUM cannot run inside a transaction block
LOCATION: PreventInTransactionBlock, xact.c:3163
=> sounds fine

[pryzbyj(at)dev ~]$ psql -c 'SELECT 1; VACUUM pg_statistic'
ERROR: VACUUM cannot run inside a transaction block
=> Error message seems off??

I couldn't figure out how to \set VERBOSITY verbose inside a psql command (??),
but strace shows for v10:
SERROR\0VERROR\0C25001\0MVACUUM cannot be executed from a function or multi-command string\0Fxact.c\0L3187\0RPreventTransactionChain

And for v11:
SERROR\0VERROR\0C25001\0MVACUUM cannot run inside a transaction block\0Fxact.c\0L3163\0RPreventInTransactionBlock

Function renamed by commit 04700b685f31508036456bea4d92533e5ceee9d6.

So behavior change maybe caused by 6eb52da3948dc8bc7c8a61cbacac14823b670c58 ?

Justin