D2600: tests: prevent enormous output spew in test-lfs-largefiles.t

[durin42 (Augie Fackler)]

durin42 created this revision.
Herald added a subscriber: mercurial-devel.
Herald added a reviewer: hg-reviewers.

REVISION SUMMARY
  This test currently fails on Python 3, but in a super-slow way. Adding
  this `head` invocation costs us nothing, but will prevent failures in
  this area from being super expensive.

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D2600

AFFECTED FILES
  tests/test-lfs-largefiles.t

CHANGE DETAILS

diff --git a/tests/test-lfs-largefiles.t b/tests/test-lfs-largefiles.t
--- a/tests/test-lfs-largefiles.t
+++ b/tests/test-lfs-largefiles.t
@@ -338,7 +338,10 @@
 No diffs when comparing merge and p1 that kept p1's changes.  Diff of lfs to
 largefiles no longer operates in standin files.
 
-  $ hg diff -r 2:3
+This `head -n 20` looks dumb (since we expect no output), but if something
+breaks you can get 1048576 lines of +y in the output, which takes a looooooong
+time to print.
+  $ hg diff -r 2:3 | head -n 20
   $ hg diff -r 2:6
   diff -r e989d0fa3764 -r 752e3a0d8488 large.bin
   --- a/large.bin	Thu Jan 01 00:00:00 1970 +0000



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Cc: mercurial-devel