libGL python meld bizarre LD_LIBRARY_PATH issue

[David Brownlee <abs%absd.org@localhost>]

This is under amd64 NetBSD-7, recent build, recent pkgsrc, base X11.

Attempting to run meld gives the following error:

Couldn't open libGL.so: Shared object "libGL.so" not found

So far so good - presumably an rpath or similar missing.

Setting

export LD_LIBRARY_PATH=/usr/X11R7/lib

and rerunning meld works.

Now it gets strange.

If I close that shell and reopen it, or just try in another shell
without *without* any LD_LIBRARY_PATH setting, meld works, and the
working persists until a reboot.