imerge: replace "merge" with "internal:merge" when non-interactive

hgext/imerge.py

@@ -120,7 +120,7 b' class Imerge(object):'
         # this could be greatly improved
         realmerge = os.environ.get('HGMERGE')
         if not interactive:
-            os.environ['HGMERGE'] = 'merge'
+            os.environ['HGMERGE'] = 'internal:merge'
 
         # The filemerge ancestor algorithm does not work if self.wctx
         # already has two parents (in normal merge it doesn't yet). But

tests/test-imerge

@@ -46,6 +46,11 b' echo % save'
 echo foo > foo2
 hg imerge save ../savedmerge
 
+echo % merge auto
+hg up -C 1
+hg --traceback imerge --auto
+cat foo2
+
 echo % load
 hg up -C 0
 hg imerge --traceback load ../savedmerge

tests/test-imerge.out

@@ -23,6 +23,20 b' all conflicts resolved'
 merging foo and foo2
 all conflicts resolved
 % save
+% merge auto
+2 files updated, 0 files merged, 0 files removed, 0 files unresolved
+2 files updated, 0 files merged, 0 files removed, 0 files unresolved
+(branch merge, don't forget to commit)
+merging foo2 and foo
+warning: conflicts during merge.
+merging foo2 failed!
+U foo2
+foo
+<<<<<<< local
+foo
+=======
+bar
+>>>>>>> other
 % load
 2 files updated, 0 files merged, 1 files removed, 0 files unresolved
 2 files updated, 0 files merged, 0 files removed, 0 files unresolved