Merge branch 'main' of https://github.com/Azure/azure-storage-azcopy …

…into dphulkar/fixDockerIssue

ste/mgr-JobMgr.go

@@ -715,7 +715,9 @@ func (jm *jobMgr) reportJobPartDoneHandler() {
 				(isCancelling && !haveFinalPart) // If we're cancelling, it's OK to try to exit early; the user already accepted this job cannot be resumed. Outgoing requests will fail anyway, so nothing can properly clean up.
 			if shouldComplete {
 				// Inform StatusManager that all parts are done.
-				close(jm.jstm.xferDone)
+				if jm.jstm.xferDone != nil {
+					close(jm.jstm.xferDone)
+				}
 
 				// Wait  for all XferDone messages to be processed by statusManager. Front end
 				// depends on JobStatus to determine if we've to quit job. Setting it here without