joco <joco@google.com> [Mon, 05 Nov 2018 22:58:19 +0100] rev 40638
mergetools: adjust Beyond Compare config on Mac/Linux
Set the labels of the Linux and Mac versions of Beyond Compare from
Mercurial's builtin variables, same as the Windows version.
Differential Revision: https://phab.mercurial-scm.org/D5255