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This partially reverts 6a5cd3ca - we keep the migration and add a new
migration that reverts it in order to keep migration history intact.

* Follow REST for merge request API route
* Remove repeating comments API for MR
Signed-off-by: NDmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

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Due to broken implementation of attribute_for_keys the runner information was not updated correctly.

This MR adds test to check that such scenario will never happen again.

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The pattern in the `::reference_pattern` class method in the
ExternalIssue model does not match all valid forms of JIRA project
names. I have updated the regex to match JIRA project names with numbers
and underscores. More information on valid JIRA project names can be
found here:
https://confluence.atlassian.com/jira/changing-the-project-key-format-192534.html

* The first character must be a letter,
* All letters used in the project key must be from the Modern Roman Alphabet and upper case, and
* Only letters, numbers or the underscore character can be used.

This has been fixed in Workhorse [ci skip]

Fixes #3951

Warning style the same as the warning a user sees on a archived project.

When using ActiveRecord::Base.connection.active? without a DB
connection, we get a "PG::ConnectionBad: could not connect to server"
error because ActiveRecord::Base.connection doesn't exist. By using
ActiveRecord::Base.connected? we ensure we don't get this error if
the connection is missing, which is the all point of the
Gitlab::CurrentSettings#connect_to_db? method!

Introduced by me through !2005

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Closes #12517

Signed-off-by: NDmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Leaving out the -I option in "git grep" would cause an Error 500 because the
resulting line would include "Binary file X matches"

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Closes #6077

- Add attribution for Anton Baklanov
- Remove attributions for employees

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Fixes #2098

This commits also fixes two minor issues:
- Ensure notes that the current user is not allowed to see are not
  returned in the AJAX notes loading
- Ensure the notes counter badge is decremented of 1 instead of 2