`nix-shell -p xdot` was failing, with an error like:
builder for '/nix/store/n3yjqssn531c52sbkmpqvczmy5c0lm8n-python3.8-xdot-1.2.drv' failed with exit code 1; last 10 log lines:
import numpy
ModuleNotFoundError: No module named 'numpy'
Adding numpy uncovered another error, about not being able to initialize
gtk:
error: Test failed: <unittest.runner.TextTestResult run=1 errors=1 failures=0>
error: --- Error -------------------------------------------------------------------------------------------------------------------------------------------- nix-shell
builder for '/nix/store/brz6q1ri12z51z3l2p5d6ny2jsf3qkjg-python3.8-xdot-1.2.drv' failed with exit code 1; last 10 log lines:
raise RuntimeError(
RuntimeError: Gtk couldn't be initialized. Use Gtk.init_check() if you want to handle this case.
