Mantis import cannot handle unknown status values

After importing a mantis project, the imported bugs with a custom status are not associated to any status. This results in the error below when trying to look at the details of such an issue.
Instead, it should be possible to map an unknown status to an existing status, so that the issues can still be accessed afterwards.

Cause:
java.lang.RuntimeException: Could not find workflow status for issue AAA-1

Stack Trace: [hide]

java.lang.RuntimeException: Could not find workflow status for issue AAA-1.
at com.atlassian.jira.permission.PermissionContextImpl.getStatusGV(PermissionContextImpl.java:106)
at com.atlassian.jira.permission.PermissionContextImpl.getRelevantStepDescriptor(PermissionContextImpl.java:83)
at com.atlassian.jira.permission.WorkflowPermissionFactory.getWorkflowPermissions(WorkflowPermissionFactory.java:26)
at com.atlassian.jira.security.WorkflowBasedPermissionManager.hasPermission(WorkflowBasedPermissionManager.java:71)
at com.atlassian.jira.security.AbstractPermissionManager.hasPermission(AbstractPermissionManager.java:121)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at com.atlassian.util.profiling.object.ObjectProfiler.profiledInvoke(ObjectProfiler.java:71)
at com.atlassian.jira.config.component.SwitchingInvocationHandler.invoke(SwitchingInvocationHandler.java:28)