ARSN-392 Put metadata to a standalone null master breaks CloudServer CRUD

[nicolas2bert]

Functionally tested here: scality/cloudserver#5531

Notes:

NOTE1: This change is only impacting the "file" metadata backend logic. Similar fixes will be implemented in scality/Metadata using Arsenal.updateOrAppendNullVersionId() method.
NOTE2: null version key is handled very differently from development/7.10 to development/7.70 where:

• in development/7.10 only the old null key logic is supported whereas
• in development/7.70 both old and new null key logic are supported for backward compatibility.
  This change won't be forward-ported to development/7.70. We will create a different PR: ARSN-392 [7.70] Put metadata to a standalone null master breaks CloudServer CRUD #2216 targeting development/7.70.

Description:

cbe6a5e: File backend should be "mocking" the V0 metadata backend. To fix it, we imported the V0 processVersionSpecificPut from scality/Metadata.

46258bc:

• Add the nullVersionId field into the master update. The nullVersionId is needed for listing, retrieving, and deleting null versions.

• Manage scenarios in which a version is marked with the isNull attribute set to true, but without a version ID.
  It happens after BackbeatClient.putMetadata() is applied to a standalone null master.

[bert-e]

Hello nicolas2bert,

My role is to assist you with the merge of this
pull request. Please type @bert-e help to get information
on this process, or consult the user documentation.

Status report is not available.

[bert-e]

Incorrect fix version

The Fix Version/s in issue ARSN-392 contains:

• None

Considering where you are trying to merge, I ignored possible hotfix versions and I expected to find:

• 7.10.58

• 7.70.24

• 8.1.123

Please check the Fix Version/s of ARSN-392, or the target
branch of this pull request.

[bert-e]

Request integration branches

Waiting for integration branch creation to be requested by the user.

To request integration branches, please comment on this pull request with the following command:

/create_integration_branches

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create the integration branches.

[jonathan-gramain]

LGTM, just a few suggestions to improve the moved code

[nicolas2bert]

/create_integration_branches

[bert-e]

Conflict

A conflict has been raised during the creation of
integration branch w/7.70/bugfix/ARSN-392/null with contents from bugfix/ARSN-392/null
and development/7.70.

I have not created the integration branch.

Here are the steps to resolve this conflict:

 $ git fetch
 $ git checkout -B w/7.70/bugfix/ARSN-392/null origin/development/7.70
 $ git merge origin/bugfix/ARSN-392/null
 $ # <intense conflict resolution>
 $ git commit
 $ git push -u origin w/7.70/bugfix/ARSN-392/null

The following options are set: create_integration_branches

[bert-e]

Integration data created

I have created the integration data for the additional destination branches.

• this pull request will merge bugfix/ARSN-392/null into
  development/7.10
• w/7.70/bugfix/ARSN-392/null will be merged into development/7.70
• w/8.1/bugfix/ARSN-392/null will be merged into development/8.1

The following branches will NOT be impacted:

• development/6.4
• development/7.4

You can set option create_pull_requests if you need me to create
integration pull requests in addition to integration branches, with:

@bert-e create_pull_requests

The following options are set: create_integration_branches

[bert-e]

Waiting for approval

The following approvals are needed before I can proceed with the merge:

• the author

• 2 peers

The following options are set: create_integration_branches

[nicolas2bert]

@bert-e approve

[bert-e]

In the queue

The changeset has received all authorizations and has been added to the
relevant queue(s). The queue(s) will be merged in the target development
branch(es) as soon as builds have passed.

The changeset will be merged in:

• ✔️ development/7.10

• ✔️ development/7.70

• ✔️ development/8.1

The following branches will NOT be impacted:

• development/6.4
• development/7.4

There is no action required on your side. You will be notified here once
the changeset has been merged. In the unlikely event that the changeset
fails permanently on the queue, a member of the admin team will
contact you to help resolve the matter.

IMPORTANT

Please do not attempt to modify this pull request.

• Any commit you add on the source branch will trigger a new cycle after the
  current queue is merged.
• Any commit you add on one of the integration branches will be lost.

If you need this pull request to be removed from the queue, please contact a
member of the admin team now.

The following options are set: approve, create_integration_branches

[bert-e]

I have successfully merged the changeset of this pull request
into targetted development branches:

• ✔️ development/7.10

• ✔️ development/7.70

• ✔️ development/8.1

The following branches have NOT changed:

• development/6.4
• development/7.4

Please check the status of the associated issue ARSN-392.

Goodbye nicolas2bert.