state: raise CorruptedState error isntead of ProgrammingError

There are old state files which don't have a version number in top of them and
hence we have to read them to check whether they are good or not.
ProgrammingError is not apt for this case. Thanks to Yuya for suggesting
CorruptedState error.

Differential Revision: https://phab.mercurial-scm.org/D3644

mercurial/state.py

@@ -72,8 +72,8 b' class cmdstate(object):'
             try:
                 int(fp.readline())
             except ValueError:
-                raise error.ProgrammingError("unknown version of state file"
-                                             " found")
+                raise error.CorruptedState("unknown version of state file"
+                                           " found")
             return cbor.load(fp)
 
     def delete(self):