(inspired by martin-brennan's recent adventure with `tags` exclusion)
**tl;dr: some of it is obsolete, some is dev-env specific and should live in *your* ~/.gitignore.**
---
To enable global gitignore (`~/.gitignore`) run:
```bash
git config --global core.excludesFile '~/.gitignore'
```
Then create that file and add your VIM/VSCode/Sublime/Emacs/Eclipse/RubyMine/JetBrains/macOS/Arch/Windows 95-specific stuff.
---
Reasons for removal:
* `bin` - never really ignored, all the files are checked in
* `.DS_Store`, `._.DS_Store` - OS specific
* `.sass-cache/*`, `/.bundle`, `/bundle/*`, `/cache`, `/logfile`, `!/plugins/discourse-nginx-performance-report`, `MiniProfiler/Ruby/rack-mini-profiler-2.0.1a.gem`, `config/fog_credentials.yml`, `/public/stylesheet-cache/*`, `script/download_db`, `script/refresh_db`, `config/version.rb` - no longer used?
* `/log/*.log` - covered by /log
* `bootsnap-load-path-cache`, `bootsnap-compile-cache` - bootsnap now keeps its ~~trash~~ temporary files in `/tmp`
* `/.project`, `/.buildpath`, `/.byebug_history`, `/.idea`, `discourse.sublime-workspace`, `*~`, `*.swp`, `*.swo`, `*.swm`, `config/multisite1.yml`, `.rvmrc`, `.ruby-version`, `.ruby-gemset`, `.rbenv`, `bundler_stubs/*`, `*.db`, `*.iml`, `*.swn`, `/package-lock.json`, `.vscode`, `.envrc`, `tags` - dev-env specific, see the note at the top of the commit
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