Finding the last merge point between branches in Mercurial

When merging between my development and release branches, I like to know what the last merge point was between the two so that I can do tasks like compile Release Notes or see if some code needs to be merged (based on tags).

I developed a little Hg alias that finds the last merge node between two branches.

lastmerge = !hg log -r "children(ancestor($1, $2)) and merge() and ::$2"

$ hg lastmerge BRANCH_1 BRANCH_2

In the example above, BRANCH_1 and BRANCH_2 are bookmarks. The alias makes use of Hg Revsets to find the latest merge node from BRANCH_1 into BRANCH_2