Merge 8-3-stable branch changes into master

Closes #155

See merge request gitlab-org/gitlab-shell!245

Display helpful feedback when proxying an SSH git push to secondary request

See merge request gitlab-org/gitlab-shell!244

This also cleans up the output from the tests as previously, Base64 encoded output was printed.

Release GitLab Shell v8.3.2

See merge request gitlab-org/gitlab-shell!243

Fix newlines not appearing between new log entries

Closes gitlab-com/gl-infra/infrastructure#5017

See merge request gitlab-org/gitlab-shell!242

In https://gitlab.com/gitlab-com/gl-infra/infrastructure/issues/5017, we
observed that lots of log messages were being dropped by Fluentd due to
missing newlines.

This occurs because there is a bug in Ruby where IO#puts calls write() twice:
once to write the main text, and another to write the newline
(https://bugs.ruby-lang.org/issues/14042). In a highly concurrent environment
like GitLab.com, this can lead to interleaved newlines.

A workaround is to use `IO#print` and append the newline ourselves.

Closes https://gitlab.com/gitlab-com/gl-infra/infrastructure/issues/5017

Merge branch '154-ensure-http-status-codes-are-integers-add-missing-specs-for-various-handled-http-status-code' into 'master'

Ensure text/plain & text/html content typs are handled and add missing specs for handled HTTP status codes

Closes #154

See merge request gitlab-org/gitlab-shell!239

Ensure text/plain & text/html content typs are handled and add missing specs for handled HTTP status codes

Release 8.3.1 to fix version numbering

See merge request gitlab-org/gitlab-shell!241

Release v8.3.0

See merge request gitlab-org/gitlab-shell!240

Includes custom action support for proxying SSH to a Geo secondary

Custom Action support

See merge request gitlab-org/gitlab-shell!215

Release gitlab-shell v8.2.1

See merge request gitlab-org/gitlab-shell!238

GitlabConfig spec was relying upon real config.yml

Proper HTTP status code support for /api/v4/allowed API endpoint

Closes gitlab-ce#51211

See merge request gitlab-org/gitlab-shell!237

* Previously, a 200 (OK) was sent when the user was unauthorised or the project was not found (or the user didn't have access)
* We still treat 401 and 404 as 'success' but we need to explicitly handle them

Release gitlab-shell v8.2.0

Closes #153

See merge request gitlab-org/gitlab-shell!236

Fix handling non 200 response codes

Closes #152

See merge request gitlab-org/gitlab-shell!235

After the cleanup in https://gitlab.com/gitlab-org/gitlab-shell/merge_requests/231
gitlab-shell mishandled the non 200 response codes. This commit removes
another few lines of codes, which fixes this. Also now we test against
this case through mocking.

Fixes https://gitlab.com/gitlab-org/gitlab-shell/issues/152

Cleanup `git-upload-*` and `git-receive-*` related code

Closes gitaly#1300

See merge request gitlab-org/gitlab-shell!232

Given the gitaly-* now proxy the data from the client to the Gitaly
server, the environment variables aren't used. Therefor we don't have to
set them either. Only exception to the rule, is the GITALY_TOKEN.

These changes also remove the `GIT_TRACE` options, introduced by
192e2bd3.

Part of: https://gitlab.com/gitlab-org/gitaly/issues/1300

All shell access goes through Gitaly, so dead code paths exist to
support the legacy way too.

This change mostly removes the dead code from `#process_cmd`.

Remove repo_path from GitlabShell

Closes #135

See merge request gitlab-org/gitlab-shell!231