setting proj_data_dir with PROJ 6.0.0 segfaults

[sebastic]

Context

The rebuild of the mapproxy Debian package with GDAL 2.5.0-beta1 & PROJ 6.0.0 got a segfault during the tests:

mapproxy.test.unit.test_srs.Test_1_ProjDataPath.test_dummy_srs ... Segmentation fault

Expected Behavior

No segfault

Actual Behavior

Segfault

Possible Fix

Update test for GDAL 2.5.0, see:

https://github.com/OSGeo/gdal/blob/v2.5.0beta1/gdal/MIGRATION_GUIDE.TXT

Steps to Reproduce

1. Build PROJ 6.0.0
2. Build libgeotiff 1.5.1 with PROJ 6.0.0
3. Build GDAL 2.5.0-beta1 with the above
4. Run mapproxy tests with the above

Your Environment

• Version used: 1.11.0
• Environment name and version: Python 2.7.16 with PROJ 6.0.0, libgeotiff 1.5.1 & GDAL 2.5.0-beta1
• Server type and version: N/A
• Operating System and version: Debian unstable

[olt]

Confirmed. Setting a custom data proj_data_dir can result in a segmentation fault. This is unrelated to GDAL 2.5, but likely due to the substantial changes in Proj > 4.

I was unable to find a quick fix. MapProxy needs to use the new Proj API in the mid/long term, hopefully fixing this.

Until then, the PROJ_LIB environment can be used to point to custom EPSG definitions.