diff --git a/tests/test-commit b/tests/test-commit
--- a/tests/test-commit
+++ b/tests/test-commit
@@ -85,4 +85,22 @@ hg log .
 cd ..
 cd ..
 
+cd ..
+hg init issue1049
+cd issue1049
+echo a > a
+hg ci -Ama
+echo a >> a
+hg ci -mb
+hg up 0
+echo b >> a
+hg ci -mc
+HGMERGE=true hg merge
+echo % should fail because we are specifying a file name
+hg ci -mmerge a
+echo % should fail because we are specifying a pattern
+hg ci -mmerge -I a
+echo % should succeed
+hg ci -mmerge
+
 exit 0
diff --git a/tests/test-commit.out b/tests/test-commit.out
--- a/tests/test-commit.out
+++ b/tests/test-commit.out
@@ -92,3 +92,14 @@ user:        test
 date:        Mon Jan 12 13:46:40 1970 +0000
 summary:     commit-foo-subdir
 
+adding a
+1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+created new head
+merging a
+0 files updated, 1 files merged, 0 files removed, 0 files unresolved
+(branch merge, don't forget to commit)
+% should fail because we are specifying a file name
+abort: cannot partially commit a merge (do not specify files or patterns)
+% should fail because we are specifying a pattern
+abort: cannot partially commit a merge (do not specify files or patterns)
+% should succeed