TopoGeo_addPoint: Corrupted topology: adjacent edges -2 and -2 bind different face (1 and 0)

[strk]

This is a more focused ticket for the problem reported as a comment of another ticket: ​https://trac.osgeo.org/postgis/ticket/5293#comment:6

Smallest testcase:

SELECT topology.CreateTopology ('t');
SELECT topology.TopoGeo_addLinestring('t',
  'LINESTRING(5.803580945500557 59.26346622000005,5.803580263500001 59.263465501000006)',
0);
SELECT topology.TopoGeo_addLinestring('t',
  'LINESTRING(5.803580263500001 59.263465501000006,5.8035809455 59.263466220000005,5.803580945500557 59.26346622000005)',
0);
SELECT * FROM topology.ValidateTopology('t');
SELECT topology.TopoGeo_addPoint( 't', 'POINT(5.803646305 59.263416658000004)', 0);

[Sandro Santilli <strk@…>]

In 6a175c5/git:

Improve robustness of finding distinct vertices in topology edges

Fixes #5394

Includes regression test.
Also augments precision in debug messages.

[strk]

I guess this could be backported to 3.3

[Sandro Santilli <strk@…>]

In 33ced5c/git:

Improve robustness of finding distinct vertices in topology edges

Fixes #5394 in 3.3 branch (3.3.4dev)

Includes regression test.
Also augments precision in debug messages.