[PATCH 2 of 2] pager: skip running the pager if it's set to 'cat'

[Augie Fackler]

# HG changeset patch
# User Augie Fackler <augie at google.com>
# Date 1489624466 14400
#      Wed Mar 15 20:34:26 2017 -0400
# Node ID bc0c38ec3f7be807607d4fdf871f344e7079d992
# Parent  07d488f16da6e12b225d2827f1020f32c8050a7a
pager: skip running the pager if it's set to 'cat'

Avoid useless uses of cat.

diff --git a/mercurial/ui.py b/mercurial/ui.py
--- a/mercurial/ui.py
+++ b/mercurial/ui.py
@@ -935,6 +935,9 @@ class ui(object):
         This is separate in part so that extensions (like chg) can
         override how a pager is invoked.
         """
+        if command == 'cat':
+            # Save ourselves some work.
+            return
         # If the command doesn't contain any of these characters, we
         # assume it's a binary and exec it directly. This means for
         # simple pager command configurations, we can degrade