Canceled queries on hot standby with hot_standby_feedback = on

I'm running Postgres 9.3.4 with one hot standby. The standby has
hot_standby_feedback = on configured:

SQL> select name, setting from pg_settings where name like '%standby%';
name | setting
-----------------------------+---------
hot_standby | on
hot_standby_feedback | on
max_standby_archive_delay | 0
max_standby_streaming_delay | 0
synchronous_standby_names |

In the standby log I have this:

2015-01-12 07:23:07 UTC ERROR: canceling statement due to conflict with
recovery
2015-01-12 07:23:07 UTC DETAIL: User was holding a relation lock for too
long.
2015-01-12 07:23:07 UTC STATEMENT: ... JOIN table_t1 ...

2015-01-12 08:53:28 UTC ERROR: canceling statement due to conflict with
recovery
2015-01-12 08:53:28 UTC DETAIL: User was holding a relation lock for too
long.
2015-01-12 08:53:28 UTC STATEMENT: ... JOIN table_t1 ...

On the primary I have this:

2015-01-12 07:23:07 UTC LOG: automatic vacuum of table "xxx.xxx.table_t1":
index scans: 0
pages: 0 removed, 273 remain
tuples: 155 removed, 918 remain
buffer usage: 131 hits, 78 misses, 16 dirtied
avg read rate: 5.656 MB/s, avg write rate: 1.160 MB/s
system usage: CPU 0.00s/0.00u sec elapsed 0.10 sec

2015-01-12 08:53:28 UTC LOG: automatic vacuum of table "xxx.xxx.table_t1":
index scans: 1
pages: 0 removed, 273 remain
tuples: 50 removed, 1057 remain
buffer usage: 168 hits, 48 misses, 13 dirtied
avg read rate: 6.046 MB/s, avg write rate: 1.637 MB/s
system usage: CPU 0.00s/0.00u sec elapsed 0.06 sec

I was under impression that setting hot_standby_feedback to on would
prevent query cancellation on the standby because of vacuuming on the
primary.

Is there something else I should do in order to disable query cancelation
on the standby?