EXEC: Import a git based project into the workspace in JBT (ex. git@github.com:adietish/kitchensink.git)
EXEC: Launch New application wizard from OpenShift explorer (or launch via project context menu Configure->New/Import OpenShift Application).
EXEC: Choose basic cartridge and click Next button (ex. EAP 6).
EXEC: Fill in name on the next wizard page and click Next.
EXEC: Choose Use existing project and select the existing git based project.
EXEC: Finish the wizard.

RESULT: There is the error that there are uncommitted changes and it is required to commit them first. Application on OpenShift is default (from basic cartridge).

This is expected as you cannot merge into a project with uncommitted changes. But the missing requirement (clean project without uncommitted changes) can be spotted far earlier when the existing project is selected.