Clean up a bare except: clause.
diff --git a/Lib/mhlib.py b/Lib/mhlib.py
index 0302c30..c83b637 100644
--- a/Lib/mhlib.py
+++ b/Lib/mhlib.py
@@ -530,7 +530,7 @@
             try:
                 toseq = tosequences[name]
                 new = 0
-            except:
+            except KeyError:
                 toseq = []
                 new = 1
             for fromn, ton in refileditems: