Use util.always instead of creating a new lambda function in show_changeset
and simplify the expression.
--- a/mercurial/cmdutil.py
+++ b/mercurial/cmdutil.py
@@ -524,9 +524,7 @@ def show_changeset(ui, repo, opts, buffe
# options
patch = False
if opts.get('patch'):
- patch = lambda x: True
- if matchfn:
- patch = matchfn
+ patch = matchfn or util.always
br = None
if opts.get('branches'):