fix failure during redownload attempt

direct/src/p3d/PackageInfo.py

@@ -509,7 +509,7 @@ class PackageInfo:
             # Try again.
             if not self.downloadDescFile(http):
                 return False
-            assert self.installPlans
+
             token = self.__followInstallPlans()
 
         if token == self.stepFailed:
@@ -523,6 +523,9 @@ class PackageInfo:
         """ Performs all of the steps in self.installPlans.  Returns
         one of stepComplete, stepFailed, or restartDownload. """
 
+        if not self.installPlans:
+            self.__buildInstallPlans()
+
         installPlans = self.installPlans
         self.installPlans = None
         for plan in installPlans: