Bundler no longer needs to be in the `$LOAD_PATH` once a version of
itself has been loaded.

In any case, the `Metadata` source takes care of adding `bundler` to the
index:

https://github.com/bundler/bundler/blob/e70643c1be3a4417bd537d7e63470265465e693e/lib/bundler/source/metadata.rb#L13-L30

and then that spec is added to the resolution here:

https://github.com/bundler/bundler/blob/e70643c1be3a4417bd537d7e63470265465e693e/lib/bundler/definition.rb#L180-L184

And from the resulting set of specs, the `$LOAD_PATH` is setup:

https://github.com/bundler/bundler/blob/e70643c1be3a4417bd537d7e63470265465e693e/lib/bundler/runtime.rb#L25-L38

So `bundler` will be present in the `$LOAD_PATH` anyways, and the lines
being removed here will never be useful.

7411: Try out specs against MRI 2.6 + Rubygems 3.0 r=deivid-rodriguez a=deivid-rodriguez

### What was the end-user problem that led to this PR?

The problem was that our Azure build was using outdated versions of ruby and rubygems.

### What was your diagnosis of the problem?

My diagnosis was that we should update them.

### What is your fix for the problem, implemented in this PR?

My fix is to update them. With the latest versions, failures go down to 319.


Co-authored-by: David Rodríguez <deivid.rodriguez@riseup.net>

7404: Support multiple groups for --without-group and --only-group options … r=deivid-rodriguez a=fatkodima

This is a reworked version of #6939 
It accepts multiple groups for `--without-group` and `--only-group`.

Closes #6939 

Co-authored-by: fatkodima <fatkodima123@gmail.com>

7399: Fix some realworld specs testing nothing r=deivid-rodriguez a=deivid-rodriguez

### What was the end-user problem that led to this PR?

The problem was that this helper was printing nothing to the standard output, so the specs in this file were just checking if lockfiles contained the empty string, which is obviously true. For example,

https://github.com/bundler/bundler/blob/e70643c1be3a4417bd537d7e63470265465e693e/spec/realworld/edgecases_spec.rb#L31

### What was your diagnosis of the problem?

My diagnosis was that the helper needs to actually print the extracted information about the resolved gem, so it can be checked that the lockfile is correct.

### What is your fix for the problem, implemented in this PR?

My fix adds the missing `puts`.

Co-authored-by: David Rodríguez <deivid.rodriguez@riseup.net>

7401: Stop silencing output by default r=indirect a=deivid-rodriguez

### What was the end-user problem that led to this PR?

The problem was that bundler defaults to a silent UI:

https://github.com/bundler/bundler/blob/e70643c1be3a4417bd537d7e63470265465e693e/lib/bundler.rb#L66-L68

In my opinion, this isn't a good behavior for a CLI tool, and forces us to override it in many many different places. It has also caused several issues, for example, https://github.com/bundler/bundler/issues/3710 where `bundle list` was printing nothing.

The [solution to that issues](https://github.com/bundler/bundler/pull/3707) led us to add yet more places where we override the default UI, and @indirect [predicting that having to unset the UI everytime we want it to not be silent](https://github.com/bundler/bundler/pull/3707#issuecomment-108646127) would cause many headaches.

Well, yeah... I've lost a lot of time trying to figure out why UI was silent sometimes, and normal another times, why some specs printed warnings and some didn't. In particular, see my series of "big fail PRs" fighting against bundler's UI: https://github.com/bundler/bundler/pull/7284, https://github.com/bundler/bundler/pull/7294, https://github.com/bundler/bundler/pull/7305, https://github.com/bundler/bundler/pull/7362.

Another series of issues/PRs probably related to this is issue https://github.com/bundler/bundler/issues/6900, where the output would use a different UI on different environments. We had a lot of trouble to reliably fix it (https://github.com/bundler/bundler/pull/6994, https://github.com/bundler/bundler/pull/7002, https://github.com/bundler/bundler/issues/7253).

I also run into these issues again when trying out the `RUBYGEMS_GEMDEPS` environment variable that enables `bundler/setup` from rubygems.

### What was your diagnosis of the problem?

My diagnosis was that we shouldn't silence UI by default.

### What is your fix for the problem, implemented in this PR?

My fix is to, instead of silencing and then overriding the default shell at many places, don't silence it by default and instead make it silent when needed. By doing this, I managed to get 100% of our specs green, so I'm pretty confident that the output is still the same (or if it's not, it's probably because some output/errors where being unintentionally swallowed). 

Now specs should pass, but they print a bunch of output to the screen. You can see error messages, hard crashes, success messages... Some of them might be showing actual issues with either the code or tests, so I plan to go through each of them and review them. I can do that in this PR or separately, no strong opinion.

Co-authored-by: David Rodríguez <deivid.rodriguez@riseup.net>

7410: November man pages r=deivid-rodriguez a=deivid-rodriguez

### What was the end-user problem that led to this PR?

The problem was that man pages are outdated after the month change.

Well, the problem actually is that I need to fix in a better way (like a monthly scheduled rebuild or something), but I keep just updating the man pages every month... :sweat_smile:

### What is your fix for the problem, implemented in this PR?

My fix to run `bin/rake man:build` and commit the result.


Co-authored-by: David Rodríguez <deivid.rodriguez@riseup.net>