merged two branches, and pushed, how to backout/strip?

[Uwe Brauer]

   > Uwe Brauer writes:


   > What’s your current branch?

default
   > What happens if you merge this into the other branch?

You mean 
 Hg merge vs-11.89
abort: merging with a working directory ancestor has no effect

Or do you mean

Hg up vs-11.89

Hg merge default?
Result:


@    changeset:   8:93ab30d908ca
|\   branch:      vs-11.89
| |  tag:         tip
| |  parent:      4:c809ddae1c8c
| |  parent:      7:fb62d04ea51b
| |  user:        Uwe Brauer <oub at mat.ucm.es>
| |  date:        Tue Jan 10 19:51:23 2017 +0000
| |  summary:     hg up vs-11.89 hg merge default
| |
| o  changeset:   7:fb62d04ea51b
| |  user:        Uwe Brauer <oub at mat.ucm.es>
| |  date:        Tue Jan 10 19:51:22 2017 +0000
| |  summary:     backout the backout
| |
| o  changeset:   6:66da55eb2d69
| |  user:        Uwe Brauer <oub at mat.ucm.es>
| |  date:        Tue Jan 10 19:51:21 2017 +0000
| |  summary:     backout bad merge from default
| |
| o  changeset:   5:6de1bb1d92a4
|/|  parent:      1:fe30ffd13c51
| |  parent:      4:c809ddae1c8c
| |  user:        Uwe Brauer <oub at mat.ucm.es>
| |  date:        Tue Jan 10 19:50:07 2017 +0000
| |  summary:     Bad merge

While your instructions result in the following graph 
@  changeset:   8:4926a89804ab
|  branch:      vs-11.89
|  tag:         tip
|  user:        Uwe Brauer <oub at mat.ucm.es>
|  date:        Tue Jan 10 19:50:56 2017 +0000
|  summary:     backout the backout
|
o    changeset:   7:a67544db15f9
|\   branch:      vs-11.89
| |  parent:      4:c809ddae1c8c
| |  parent:      6:6d5b6d21ebfd
| |  user:        Uwe Brauer <oub at mat.ucm.es>
| |  date:        Tue Jan 10 19:50:53 2017 +0000
| |  summary:     merge default with the backout
| |
| o  changeset:   6:6d5b6d21ebfd
| |  user:        Uwe Brauer <oub at mat.ucm.es>
| |  date:        Tue Jan 10 19:50:52 2017 +0000
| |  summary:     backout bad merge
| |
| o  changeset:   5:6de1bb1d92a4
|/|  parent:      1:fe30ffd13c51
| |  parent:      4:c809ddae1c8c
| |  user:        Uwe Brauer <oub at mat.ucm.es>
| |  date:        Tue Jan 10 19:50:07 2017 +0000
| |  summary:     Bad merge


The content of the files is the same however.

Uwe