6631003: Add hg tip changeset to build image

Reviewed-by: mduigou
diff --git a/corba/.hgignore b/corba/.hgignore
index 0092bd4..83cef21 100644
--- a/corba/.hgignore
+++ b/corba/.hgignore
@@ -1,3 +1,4 @@
 ^build/
 ^dist/
 /nbproject/private/
+^.hgtip