$ psql -p 5416 -a -f test.sql
\setenv PSQL_EDITOR 'vim'
\setenv PSQL_EDITOR_LINENUMBER_ARG '+'
\set ON_ERROR_ROLLBACK 'interactive'
\set ON_ERROR_STOP 'on'
--\set SHOW_CONTEXT 'always'
\set PROMPT1 '%[%033[38;5;'`echo $PROMPT_COLOR`'m%]%x%n@%m:%>/%/\n%R%# %[%033[m%]'
\set PROMPT2 '%[%033[38;5;'`echo $PROMPT_COLOR`'m%]%R%# %[%033[m%]'
BEGIN;
BEGIN
CREATE TABLE parent (
	id	int primary key
) PARTITION BY RANGE (id);
CREATE TABLE
CREATE TABLE parent_0 PARTITION OF parent
	FOR VALUES FROM (0) TO (100);
CREATE TABLE
CREATE TABLE children (
	id	int primary key references parent(id)
) PARTITION BY RANGE (id);
CREATE TABLE
CREATE TABLE children_0 PARTITION OF children
	FOR VALUES FROM (0) TO (100);
CREATE TABLE
DROP TABLE children_0;
DROP TABLE
DROP TABLE parent_0;
psql:test.sql:15: ERROR:  cannot drop table parent_0 because other objects depend on it
DETAIL:  constraint children_id_fkey on table children depends on table parent_0
HINT:  Use DROP ... CASCADE to drop the dependent objects too.

Looked like a bug.