[PATCH 1 of 8] tests: adjust merge tool config in test-largefiles-update.t

[Boris Feld]

# HG changeset patch
# User Boris Feld <boris.feld at octobus.net>
# Date 1541007836 -3600
#      Wed Oct 31 18:43:56 2018 +0100
# Node ID d01a6df50fa2c5432f2040afe686e05062e02cce
# Parent  909c31805f54628ab5bf22cd92418c8ac9c09277
# EXP-Topic run-tests
# Available At https://bitbucket.org/octobus/mercurial-devel/
#              hg pull https://bitbucket.org/octobus/mercurial-devel/ -r d01a6df50fa2
tests: adjust merge tool config in test-largefiles-update.t

Previously, the `ui.merge=internal:fail` configuration was shadowed by the the
`HGMERGE=internal:merge` environment variable. We would like to remove this
usage of `HGMERGE` variable because it is error-prone (eg: this very test). We
start by cleaning up test independently to avoid large churn when the change
happens.

diff --git a/tests/test-largefiles-update.t b/tests/test-largefiles-update.t
--- a/tests/test-largefiles-update.t
+++ b/tests/test-largefiles-update.t
@@ -3,9 +3,10 @@
 This file focuses mainly on updating largefiles in the working
 directory (and ".hg/largefiles/dirstate")
 
+  $ unset HGMERGE
   $ cat >> $HGRCPATH <<EOF
   > [ui]
-  > merge = internal:fail
+  > merge = internal:merge
   > [extensions]
   > largefiles =
   > [extdiff]