Created attachment 1788812 [details]
The error screenshot.

Description of problem:
Try to migrate two projects in one migplan in the web console, when going to “”Namespace” phase, change the namespace in the target cluster for both projects. Map the first project from “A” to “A-map”, then map the second project from “B” to “B-map”. But when changing the namespace for the second project, the web console throws out an incorrect error message. 


Version-Release number of selected component (if applicable):
MTC 1.5.0

How reproducible:
Always

Prepare two projects in source cluster 
$ ansible-playbook deploy-app.yml -e use_role=ocp-nginxpv -e namespace=ocp-22222-nginx
$ ansible-playbook deploy-app.yml -e use_role=ocp-cakephp -e namespace=ocp-00000-pv-image

Create one migplan to migrate above two projects at the same time in web console
When the page goes to the “Namespace” phase, try to change the namespace of these two projects one by one.  
ocp-00000-pv-image to ocp-00000-pv-image-target 
ocp-22222-nginx to ocp-22222-nginx-target

When changing the  namespace for the second project ocp-22222-nginx, first input “ocp-22222-nginx-a”, then delete last characters back to “ocp-22222-nginx”, will get an error message “A mapped target namespace with that name already exists. Enter a unique name for this target namespace.”

Actual results:
When changing the  namespace for the second project ocp-22222-nginx, first input “ocp-22222-nginx-a”, then delete last characters back to “ocp-22222-nginx”, will get an error message “A mapped target namespace with that name already exists. Enter a unique name for this target namespace.”  In fact “ocp-22222-nginx”  did not exist. 

Check the attachment to get the screen shot.

Expected results:
The web console should not throw out this error message.

Additional info:
In target cluster 
$ oc get ns|grep ocp-22222-nginx  
$            <------- without ocp-22222-nginx