Teach GitLab not only to merge changes from a merge-request, but also to
apply patches posted to merge-request in a way like `git am` would do -
without merge commit and directly on top of current branch. Which way to
go is selected by user in web UI, and apply patches is the first option.

There are 3 cases:

- only 1 commit is present in MR -> the only available option is to
  apply that single commit as one patch without a merge

  ( There is no need for merge commit in this case at all: information
    about user who applied the patch goes to "Committer" field in resultant
    commit. Avoiding 1 merge per 1 patch results in cleaner history )

  It is also possible to review patch description directly in web UI,
  before doing the actual application, and correct / amend it as needed.

- several commits are present in MR:

  * it is possible to apply the patches directly on top of current
    branch. Again information about who applied what goes to "Committer"
    field.

  * it is possible to merge MR changes with making a merge commit.

    This variant is useful, when patches from a MR do several logical
    steps to reach one goal, and MR description contain cover letter for
    whole patch series.

    in this case original commits stay untouched and resulting merge
    will contain MR author as author, user who accepted MR as committer,
    and cover letter as merge commit message.

    NOTE we avoid useless "Merge branch X into Y" in merge message, and
        just put MR title into merge subject and MR description into merge
        description.

        This way it is more logical with more important information in
        merge subject and thus e.g. more handy to oversee what a merge brings,
        just by it subject, e.g. via looking at updates via

            gitk --first-parent ...

        or via web.

NOTE for pre-generated references to merge-request we now use full MR
    URL, instead of !<MR-n>. Full URLs work everywhere, not only on
    original site where MR was created, or even only in original repo
    and not its fork on the same site.

94ddf244
fixup! NXD Teach GitLab about patches

commit_with_hooks was replaced by GitOperationService: see https://gitlab.com/gitlab-org/gitlab-ce/commit/a52dc7cec70ef97b2755fb9cef7d6b489062310c

12a773b6
fixup! NXD Teach GitLab about patches: include merge description message

Include Merge description message in apply_patches and merge as topic by default. User can disable description in merge message by clicking on `Don't include description in commit message`.

/reviewed-on !4

From gitlab 8.12 there is new CI job permissions model which only accept login
from ci token for running job. Then the access is revoked after the job is finished.
In Nexedi, when have a lot of URLs which rely on gitlab-ci-token and project-runners-token, so
we need to re-allow access else access to all those URL will be refused.

More info are here: https://docs.gitlab.com/ee/user/project/new_ci_build_permissions_model.html#before-gitlab-8-12

TODO detect whether request comes from China and only then show ICP (?).

We show in small font size the same info that is shown on sign_in page:

    "GitLab Nexedi Edition", "About GitLab" and "About Nexedi"

This is good to have and hereby-introduced about-footer area will be
also used in the next patch for ICP too.

XXX placement of .about-footer to be near bottom is done not very
correctly.

The default was switched to HTTP in the previous patch, but let's completely
remove SSH option - we support only HTTP for git fetch/push.

Conflicts:
	app/views/shared/_clone_panel.html.haml

Both fetch and push are possible over https, which is selected by http if
gitlab was configured to use https in external url.

This way to reduce security vectors and possible ways to interact with gitlab
we use https only without ssh at all.

= GitLab Community Edition + Nexedi patches

[ci skip]

(backport) Include X-Content-Type-Options (XCTO) header into API responses

See merge request gitlab/gitlabhq!2216

(cherry picked from commit 5fcb214f8527b3d58be1a833a596d01b1bf6119e)

40c6c9f4 Include X-Content-Type-Options (XCTO) header into API responses

eplace SSRF resolver with Addrinfo.getaddrinfo to include alternative localhost versions (9-5)

See merge request gitlab/gitlabhq!2221

(cherry picked from commit 53cc25eb3d45c782b5085524a8976f034ef18781)

96555882 Replace SSRF resolver with Addrinfo.getaddrinfo to include alternative localhost versions

[ci skip]

3435 backport for 9.5

See merge request gitlab/gitlabhq!2207

fix transient user_edits_files_spec failures

See merge request gitlab-org/gitlab-ce!14324

[10.0 CE] Prevent "Related Issues" from leaking confidential issues

See merge request gitlab/gitlabhq!2193

Move project repositories between namespaces when renaming users (9.5)

See merge request gitlab/gitlabhq!2202

Escape user name in filtered search bar

See merge request gitlab/gitlabhq!2195

[9.5] Prevent a persistent XSS in user-provided markup

See merge request gitlab/gitlabhq!2203

Treat newlines as separators for pipeline emails service

Closes #37759

See merge request gitlab-org/gitlab-ce!14250

Fix arbitrary redirect location vulnerability

See merge request gitlab/gitlabhq!2192

Fix arbitrary redirect location vulnerability

See merge request gitlab/gitlabhq!2192

[ci skip]

Fix fork button being disabled for users who can fork to group

Closes #38462

See merge request gitlab-org/gitlab-ce!14551

[ci skip]

Fix gitlab rake:import:repos task for 9.5.x

See merge request gitlab-org/gitlab-ce!14639

This backports !14597 for the 9.5.x branch.

Because of a change in GitLab 9.5.4 to prevent users from assuming control of
a repository already on disk, the import task broke. Imports would fail with
the message, "There is already a repository with that name on disk".

This change skips the validation when the import is done from the
command-line.

Closes #37682

[ci skip]

Handle error when fetching ref for MR with deleted source branch

See merge request gitlab-org/gitlab-ce!14550

Upgrade Nokogiri because of CVE-2017-9050

See merge request gitlab-org/gitlab-ce!14427