Merge pull request #16647 from mppf/fix-man-makefile
Follow-up to PR #16644 and #16560
- Adjust run-in-venv.bash to error messages to stderr
- Put back changes from PR #5579
- Invoke rst2man.py with the current python interpreter to avoid problems with the shebang being too long in some settings
Mostly trivial but by @ronawho - thanks!