9.3 pg_archivecleanup broken?

(In a test setup) I can't get pg_archivecleanup to remove WALfiles in 9.3devel. (A very similar
setup in 9.2 works fine).

In 9.3 pg_archivecleanup just keeps repeating lines like:

pg_archivecleanup: keep WAL file "/home/aardvark/pg_stuff/archive_dir93/000000000000000000000000"
and later

(and does not delete any files.)

Configuration:

# master pgsql.93_1/data/postgresql.conf:
data_directory = '/home/aardvark/pg_stuff/pg_installations/pgsql.93_1/data'
listen_addresses = '*'
max_connections = 100
shared_buffers = 128MB
wal_level = hot_standby
synchronous_commit = on
checkpoint_segments = 3
archive_mode = on
archive_command = 'cp %p /home/aardvark/pg_stuff/archive_dir93/%f < /dev/null'
max_wal_senders = 3
synchronous_standby_names = '*'

# slave pgsql.93_2/data/postgresql.conf:
data_directory = '/home/aardvark/pg_stuff/pg_installations/pgsql.93_2/data'
listen_addresses = '*'
port = 6665
max_connections = 100
shared_buffers = 128MB
wal_level = hot_standby
synchronous_commit = on
checkpoint_segments = 3
max_wal_senders = 3
synchronous_standby_names = ''
hot_standby = on
wal_receiver_status_interval = 59

# pgsql.93_2/data/recovery.conf
primary_conninfo = 'host=127.0.0.1 port=6664 user=aardvark password=sekr1t
application_name=wal_receiver_01'
standby_mode = 'on'
restore_command = 'cp /home/aardvark/pg_stuff/archive_dir93/%f %p < /dev/null'
archive_cleanup_command = 'pg_archivecleanup -d /home/aardvark/pg_stuff/archive_dir93 %r'

Seeing that the same setup in 9.2 has pg_archivecleanup deleting files, it would seem that some
bug exists but I haven't followed changes regarding WAL too closely.

(My apologies if it's a config mistake on my part after all; but in that case: I cannot find it
and would be thankful for a hint)

Thanks,

Erik Rijkers