practracker: Fix duplicate exceptions and handle them more "gracefully".

scripts/maint/practracker/exceptions.txt

@@ -173,7 +173,6 @@ problem function-size /src/feature/hs/hs_client.c:send_introduce1() 104
 problem function-size /src/feature/hs/hs_client.c:hs_config_client_authorization() 108
 problem function-size /src/feature/hs/hs_config.c:config_generic_service() 149
 problem function-size /src/feature/hs/hs_cell.c:hs_cell_build_establish_intro() 115
-problem function-size /src/feature/hs/hs_cell.c:hs_cell_parse_introduce2() 147
 problem file-size /src/feature/hs/hs_descriptor.c 3108
 problem function-size /src/feature/hs/hs_descriptor.c:desc_encode_v3() 108
 problem function-size /src/feature/hs/hs_descriptor.c:decrypt_desc_layer() 110

scripts/maint/practracker/problem.py

@@ -33,6 +33,12 @@ class ProblemVault(object):
             if problem is None:
                 continue
 
+            # Fail if we see dup exceptions. There is really no reason to have dup exceptions.
+            if problem.key() in self.exceptions:
+                print("Duplicate exceptions lines found in exception file:\n\t{}\n\t{}\nAborting...".format(problem, self.exceptions[problem.key()]),
+                      file=sys.stderr)
+                sys.exit(1)
+
             self.exceptions[problem.key()] = problem
             #print "Registering exception: %s" % problem