+++ This bug was initially created as a clone of Bug #1845157 +++

Description of problem:
When we execute a migration that has been previously run as "stage", the migration fails.

Version-Release number of selected component (if applicable):
CAM 1.2.2 stage
SOURCE: OCP 3.11 AWS
TARGET: OCP 4.4 AWS
AWS S3 BUCKET


How reproducible:
Always

Steps to Reproduce:
1. Create a namespace with a nginx application

oc process -p NAMESPACE=bztest -f  https://gitlab.cee.redhat.com/app-mig/cam-helper/raw/master/ocp-26160/nginx_with_pv_defaultsc_template.yml | oc create -f -

2. Feed the data

oc -n bztest rsh $(oc get pods -n bztest -o jsonpath='{.items[0].metadata.name}') sh -c 'echo "<h1>HELLO WORLD</h1>" > /usr/share/nginx/html/index.html'

3. Execute a "stage" migration with this namespace

4. Execute a migration with this namespace


Actual results:
The stage migration will run OK, but the actual migration will fail, and this error will be displayed in the MigMigration resource

status:
  conditions:
  - category: Advisory
    durable: true
    lastTransitionTime: "2020-06-08T12:59:10Z"
    message: '[1] Stage pods created.'
    status: "True"
    type: StagePodsCreated
  - category: Advisory
    durable: true
    lastTransitionTime: "2020-06-08T13:00:12Z"
    message: 'The migration has failed.  See: Errors.'
    reason: QuiesceApplications
    status: "True"
    type: Failed
  errors:
  - 'Operation cannot be fulfilled on replicasets.extensions "nginx-deployment-557dd97bf8":
    the object has been modified; please apply your changes to the latest version
    and try again'
  itenerary: Failed


Expected results:
The migration should be executed without problems.

Additional info:

--- Additional comment from Sergio on 2020-06-08 16:28:15 UTC ---

It doesn't seem to necessary to previously "stage" the migration. I could reproduce it consistently by staging migrations, but all of a sudden it stopped happening. Now it eventually happens in quiesced migrations, and I cannot consistently reproduce it.