Test failure with OrientedEnvelope

```
not ok 30 - ST_AsText(OrientedEnvelope(ST_GeomFromText('LINESTRING(0 0, 10 10, 8 12)')))
expected: 'POLYGON((8 12,10 10,0 0,-2 2,8 12))'
actual: 'POLYGON((2.30769230769231 -1.53846153846154,1.77635683940025e-15 -8.88178419700125e-16,8 12,10.3076923076923 10.4615384615385,2.30769230769231 -1.53846153846154))'
```

PostGIS full version is `POSTGIS="2.1.7 r13414" GEOS="3.5.0-CAPI-1.9.0 r4084" PROJ="Rel. 4.9.1, 04 March 2015" GDAL="GDAL 1.11.2, released 2015/02/10" LIBXML="2.9.2" LIBJSON="UNKNOWN" RASTER`, PostgreSQL is 9.4.4 server and client

Start by reproducing the failing ST_AsText(OrientedEnvelope(ST_GeomFromText(...))) case from the issue against the listed PostgreSQL and PostGIS versions. Compare the expected and actual polygons and inspect the relevant test setup or SQL entry point. Done means the discrepancy is explained and the test expectation or implementation is corrected with a regression check.

Written by the indexing model from the issue text.