st_removerepeatedpoints not fully working in 2.4.4

[jhaagmans]

When running PostGIS version 2.4.4 I see the following behaviour:

select ST_REMOVEREPEATEDPOINTS('POLYGON((0 0,0 1,1 1,1 1,1 0,0 0))'::geometry);
-> POLYGON ((0 0, 0 1, 1 1, 1 1, 1 0, 0 0))

(note that the second 1 1 should be removed, but isn't)

When adding a new point at 1 2 after the second 1 1, it works though:

select ST_REMOVEREPEATEDPOINTS('POLYGON((0 0,0 1,1 1,1 1,1 2,1 0,0 0))'::geometry);
-> POLYGON ((0 0, 0 1, 1 1, 1 2, 1 0, 0 0))

I discussed this on IRC where someone noted that this does work on the current 2.5.0beta, but as this is a production workload running on AWS RDS I probably shouldn't use a beta version and I thought I should report this behaviour anyway for posterity.

[pramsey]

Weird, I had an older 2.4 and ran the test and it worked. I pushed up to the svn head of the 2.4 branch it I can replicate your problem. Time for an svn blame trip.

[pramsey]

In 16977:

Proper repeated point removal for small polygons
Closes #4136