practracker: add a --regen-overbroad option to remove overbroad exceptions.

Closes ticket 32372.

scripts/maint/practracker/problem.py

@@ -29,6 +29,8 @@ class ProblemVault(object):
     def __init__(self, exception_fname=None):
         # Exception dictionary: { problem.key() : Problem object }
         self.exceptions = {}
+        # Exception list: list of Problem objects, in the order added.
+        self.exception_list = []
         # Exception dictionary: maps key to the problem it was used to
         # suppress.
         self.used_exception_for = {}
@@ -63,6 +65,7 @@ class ProblemVault(object):
                 sys.exit(1)
 
             self.exceptions[problem.key()] = problem
+            self.exception_list.append(problem)
             #print "Registering exception: %s" % problem
 
     def register_problem(self, problem):
@@ -98,6 +101,24 @@ class ProblemVault(object):
             if p is None or e.is_worse_than(p):
                 yield (e, p)
 
+    def list_exceptions_without_overbroad(self):
+        """Return an iterator of new problems, such that overbroad
+           exceptions are replaced with minimally broad versions, or removed.
+        """
+        for e in self.exception_list:
+            p = self.used_exception_for.get(e.key())
+            if p is None:
+                # This exception wasn't needed at all.
+                continue
+            if e.is_worse_than(p):
+                # The exception is worse than the problem we found.
+                # Yield the problem as the new exception value.
+                yield p
+            else:
+                # The problem is as bad as the exception, or worse.
+                # Yield the exception.
+                yield e
+
     def set_tolerances(self, fns):
         """Adjust the tolerances for the exceptions in this vault.  Takes
            a map of problem type to a function that adjusts the permitted