Branch deletion handling with Bitbucket Server

[nleach999]

Describe the problem

Newer versions of BitBucket server send a push event that indicates branch deletion. Currently, we don't gracefully handle this because the scan logic is attempted. If it is a branch name meeting the protected branch name criteria, it fails to scan because the branch is deleted.

This means we also don't handle the project deletion the same way as other SCMs.

Proposed solution

Implement the same logic as in GitHub to not scan delete push events and to delete SAST projects for the branch.

Additional details

This is an example payload from BB server 7.10.0. Note the "changes" section.

{
    "eventKey": "repo:refs_changed",
    "date": "2021-02-17T17:18:47+0000",
    "actor": {
        "name": "admin",
        "emailAddress": "[email protected]",
        "id": 2,
        "displayName": "admin",
        "active": true,
        "slug": "admin",
        "type": "NORMAL",
        "links": {
            "self": [
                {
                    "href": "http://localhost:7990/users/admin"
                }
            ]
        }
    },
    "repository": {
        "slug": "simplyvulnerable",
        "id": 1,
        "name": "simplyvulnerable",
        "hierarchyId": "781fefd15bfb01738bb9",
        "scmId": "git",
        "state": "AVAILABLE",
        "statusMessage": "Available",
        "forkable": true,
        "project": {
            "key": "TEST",
            "id": 1,
            "name": "TEST",
            "public": false,
            "type": "NORMAL",
            "links": {
                "self": [
                    {
                        "href": "http://localhost:7990/projects/TEST"
                    }
                ]
            }
        },
        "public": false,
        "links": {
            "clone": [
                {
                    "href": "ssh://git@localhost:7999/test/simplyvulnerable.git",
                    "name": "ssh"
                },
                {
                    "href": "http://localhost:7990/scm/test/simplyvulnerable.git",
                    "name": "http"
                }
            ],
            "self": [
                {
                    "href": "http://localhost:7990/projects/TEST/repos/simplyvulnerable/browse"
                }
            ]
        }
    },
    "changes": [
        {
            "ref": {
                "id": "refs/heads/demo-dev",
                "displayId": "demo-dev",
                "type": "BRANCH"
            },
            "refId": "refs/heads/demo-dev",
            "fromHash": "3cf2a5016a71ff880ed62a7058bdfdbd620fe6ab",
            "toHash": "0000000000000000000000000000000000000000",
            "type": "DELETE"
        }
    ]
}

[HussainS12]

This is fixed in PR #932