test-merge-types: allow different output with existing hgmerge (issue3346) stable

test-merge-types: allow different output with existing hgmerge (issue3346)

Because hgmerge was meant to be adjusted to personal needs, there may be
many remaining copies in people's $PATH.

--- a/tests/test-merge-types.t	Wed Apr 04 10:57:48 2012 +0200
+++ b/tests/test-merge-types.t	Wed Apr 04 11:18:42 2012 +0200
@@ -89,7 +89,7 @@
    a: versions differ -> m
   preserving a for resolve of a
   updating: a 1/1 files (100.00%)
-  couldn't find merge tool hgmerge
+  (couldn't find merge tool hgmerge|tool hgmerge can't handle symlinks) (re)
   picked tool 'internal:prompt' for a (binary False symlink True)
    no tool found to merge a
   keep (l)ocal or take (o)ther? l