Improving robustness

[sam-grant]

Things to improve

• Be more careful when allowing packages to be managed by pip, this can cause dependancy issues
• Some packages that are pinned to very old versions (inherited from the pyana), which might be causing problems
• Pay more attention to priority given to packages in the YAML file, this is more important than I'd realised
• Instead of stacking environment variables patches in setup-mu2e-env.sh, test if broken paths can be resolved with conda-unpack after activating the unpacked environment