Proposed fix for 3389764. Have "path" dup routine duplicate the pattern

of a value with a cyclic reference to itself.  Don't keep a reference to
the value getting dup'd so the assumptions of cycle prevention in bytecode
compilation are satisfied.

generic/tclPathObj.c

@@ -2617,29 +2617,29 @@ DupFsPathInternalRep(
 
     SETPATHOBJ(copyPtr, copyFsPathPtr);
 
-    if (srcFsPathPtr->translatedPathPtr != NULL) {
+    if (srcFsPathPtr->translatedPathPtr == srcPtr) {
+	/* Cycle in src -> make cycle in copy. */
+	copyFsPathPtr->translatedPathPtr = copyPtr;
+    } else {
 	copyFsPathPtr->translatedPathPtr = srcFsPathPtr->translatedPathPtr;
-	if (copyFsPathPtr->translatedPathPtr != copyPtr) {
+	if (copyFsPathPtr->translatedPathPtr != NULL) {
 	    Tcl_IncrRefCount(copyFsPathPtr->translatedPathPtr);
 	}
-    } else {
-	copyFsPathPtr->translatedPathPtr = NULL;
     }
 
-    if (srcFsPathPtr->normPathPtr != NULL) {
+    if (srcFsPathPtr->normPathPtr == srcPtr) {
+	/* Cycle in src -> make cycle in copy. */
+	copyFsPathPtr->normPathPtr = copyPtr;
+    } else {
 	copyFsPathPtr->normPathPtr = srcFsPathPtr->normPathPtr;
-	if (copyFsPathPtr->normPathPtr != copyPtr) {
+	if (copyFsPathPtr->normPathPtr != NULL) {
 	    Tcl_IncrRefCount(copyFsPathPtr->normPathPtr);
 	}
-    } else {
-	copyFsPathPtr->normPathPtr = NULL;
     }
 
-    if (srcFsPathPtr->cwdPtr != NULL) {
-	copyFsPathPtr->cwdPtr = srcFsPathPtr->cwdPtr;
+    copyFsPathPtr->cwdPtr = srcFsPathPtr->cwdPtr;
+    if (copyFsPathPtr->cwdPtr != NULL) {
 	Tcl_IncrRefCount(copyFsPathPtr->cwdPtr);
-    } else {
-	copyFsPathPtr->cwdPtr = NULL;
     }
 
     copyFsPathPtr->flags = srcFsPathPtr->flags;