Ticket 50117 - after certain failed import operation, impossible to replay an import operation
    
    Bug Description:
    	At the beginning of an import, a flag is set to mark the target backend is busy.
    	Then import tests if there are pending operations. If such operations exist the import can not proceed and fails.
    	The problem is that in such case of pending operations, the import fails without resetting the busy flag.
    	It let the backend busy (until next reboot) and prevent new import.
    
    Fix Description:
    	It needs to reset the busy flag if there are pending operations
    
    https://pagure.io/389-ds-base/issue/50117
    
    Reviewed by: Mark Reynolds, William Brown
    
    Platforms tested: F27
    
    Flag Day: no
    
    Doc impact: no
    
    (cherry picked from commit ff00b07402747aac403478a157adab75e306d7d1)
    (cherry picked from commit 630940ec119a90c3bbfc7cd3464eb02ab779b474)