hgwebdir: handle IOErrors from localrepo while enumerating

Repository() raises a number of IOErrors in addition to RepoErrors.
 these are just as uninteresting as RepoErrors and should be ignored

The easiest case of this is a repo whose .hg/ directory is -rx

mercurial/hgweb/hgwebdir_mod.py

@@ -251,6 +251,9 b' class hgwebdir(object):'
                 # update time with local timezone
                 try:
                     r = hg.repository(self.ui, path)
+                except IOError:
+                    u.warn(_('error accessing repository at %s\n') % path)
+                    continue
                 except error.RepoError:
                     u.warn(_('error accessing repository at %s\n') % path)
                     continue