Thanks for your questions. I will be happy to clarify the issue. It should be clear though that I don't have two different installations of gnuradio on any single machine at any point in time.
This is what I'm doing. My goals are to install and run gnuradio. My distribution, as I wrote earlier, is Debian testing, codenamed Buster. My previous installation I had since last Summer was compiled from source and was working without any Python environment errors. Unfortunately I removed that installation in order to install the latest gnuradio. And that one didn't work.
Ways I tried, each one after removing any other gnuradio installations:
1. Install from package: sudo apt install gnuradio. Installation successful. gnuradio-companion displays the error dialog and exits.
2. build-gnuradio. Compilation of gnuradio fails because of this issue:
I fixed the issue by applying the above patch. Compilation succeeds. The error dialog is the same and gnuradio-companion still doesn't work.
3. Compile gnuradio from github. Managed to compile but same error dialog.
Furthermore, in each of the 3 cases above I first tried running gnuradio-companion with the default environment: LD_LIBRARY_PATH and PYTHONPATH _empty_. When that didn't work, I set the environment according to the README and to my Python version:
$ export PYTHONPATH=/usr/local/lib/python2.7/dist-packages
$ export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$HOME/local/lib
which didn't change the outcome a bit.
For the sake of completeness, the dialog text is the following:
======
Cannot import gnuradio.
Is the model path environment variable set correctly?
All OS: PYTHONPATH
Is the library path environment variable set correctly?
Linux: LD_LIBRARY_PATH
Windows: PATH
MacOSX: DYLD_LIBRARY_PATH
(No module named _runtime_swig)
======
Any ideas apart from changing the Linux distribution? The distro has to stay. I can always go back to the version of gnuradio that worked but I have a feeling that the issue here is very minor and can be fixed if you know the details.
--Vladimir