clfilter: stronger detection of filtered changeset in changectx.__init__

We previously let some IndexError spill out of this function.

A new tests is added to check the command that spotted the error.

mercurial/context.py

@@ -67,7 +67,7 b' class changectx(object):'
             self._rev = r
             self._node = repo.changelog.node(r)
             return
-        except (ValueError, OverflowError):
+        except (ValueError, OverflowError, IndexError):
             pass
 
         if len(changeid) == 40:

tests/test-obsolete.t

@@ -186,6 +186,23 b' check that summary does not report them'
   update: 3 new changesets, 4 branch heads (merge)
   remote: 3 outgoing
 
+check that various commands work well with filtering
+
+  $ hg tip
+  changeset:   5:5601fb93a350
+  tag:         tip
+  parent:      1:7c3bad9141dc
+  user:        test
+  date:        Thu Jan 01 00:00:00 1970 +0000
+  summary:     add new_3_c
+  
+  $ hg log -r 6
+  abort: unknown revision '6'!
+  [255]
+  $ hg log -r 4
+  abort: unknown revision '4'!
+  [255]
+
 Check that public changeset are not accounted as obsolete:
 
   $ hg --hidden phase --public 2