This is follow up of 1f7cb4bee9.

This reverts commit 67c574736912003c377218153f9d3b9c0c96a17b.
[Feature #16275]

I noticed that some files in rubygems were executable, and I could think
of no reason why they should be.

In general, I think ruby files should never have the executable bit set
unless they include a shebang, so I run the following command over the
whole repo:

```bash
find . -name '*.rb' -type f -executable -exec bash -c 'grep -L "^#!" $1 || chmod -x $1' _ {} \;
```

Tabs were expanded because previously the file did not have any tab indentation.
Please update your editor config, and use misc/expand_tabs.rb in the pre-commit hook.