I now understand what I should have done. After pulling and updating,

1. Make sure there is only 1 head per branch by using 'hg heads <branch>*. Merge all but only pairs revealed by that command.

* 'hg heads' without giving a branch lists all heads in all branches, including 2.6 and 3.1, making it harder to find pairs in one branch. This is especially true in the Workbench command window which has room to see only one head at a time. So I recommend you at least mention the option of adding the branch (with 3.4 being 'default').

Comment: while 2 heads for 2.7 or default are visibly obvious in the dag (at least they were the one time I had such), 2 heads for 3.2 and 3.3 seems not to be, at least when merged forwards. As far as I know, the only way to tell which nodes hg considers to be heads (in particular, which node is the already pushed head) is to use the 'heads' command.

(My big mistake was to *assume* -- without checking 'heads' -- that the 3.2 heads, when merged forward, must have become 2 heads in 3.3 ...)

2. Merge forward as needed. I think a version of your 6 step display would be helpful. It was for me.