test: use the "correct" merge tool in `test-rebase-detach.t`
The value of `HGMERGE` overrides the value passed through --config. We are
about to drop this `HGMERGE` environment variable so we update the value used
in config to match what is currently in use.
This is another example of confusion introduced by the `HGMERGE` environment
variable.
--- a/tests/test-rebase-detach.t Wed Oct 31 19:12:32 2018 +0100
+++ b/tests/test-rebase-detach.t Thu Nov 01 14:24:34 2018 +0100
@@ -293,7 +293,7 @@
$ hg ci -A -m 'B2'
adding B
$ hg phase --force --secret .
- $ hg rebase -s . -d B --config ui.merge=internal:fail
+ $ hg rebase -s . -d B --config ui.merge=internal:merge
rebasing 3:17b4880d2402 "B2" (tip)
merging B
warning: conflicts while merging B! (edit, then use 'hg resolve --mark')