GIN vs BTREE - query planner picking the wrong one some times

Using postgres 9.5 and I'm trying to improve performance of searches using
the LIKE operator on column containing a URL.

Consider a table like this with about 50 million rows

CREATE TABLE page_hit (
timestamp_ timestamp without time zone NOT NULL,
location_url character varying(2048)
)

and a query like this

SELECT count(*)
FROM page_hit
WHERE location_url LIKE 'http://mysite.foo.com/path/morepath%'

The above query makes use of the following index

CREATE INDEX location_idx
ON page_hit
USING btree
(location_url varchar_pattern_ops);

The works great..BUT... to support LIKE wild cards in other parts of the
string (for example a leading %) I created a GIN index as follows

CREATE INDEX location_idx_gin
ON page_hit
USING gin
(location COLLATE pg_catalog."default" gin_trgm_ops);

The problem is when I run EXPLAIN ANALYZE on the above query now its only
ever using location_idx_gin and ignoring location_idx which kinda sucks
cause the location_idx index is faster at trailing % queries. The query
planner seems to ignore my BTREE index in all cases and uses the GIN index.

The BTREE index outperforms the GIN index (in the case of a trailing %) but
I want the planner to pick the GIN index in the case of leading %. Is there
a way to do this?

Some metrics (queries trailing %):

- BTREE : <1 second explain: https://explain.depesz.com/s/7wgx
- GIN : 3.8 seconds explain: https://explain.depesz.com/s/wYhk

ᐧ