Tried to do as requested, but hg (hg qfold 20180829 20180831) refused with:
"Abbruch: qfold kann den bereits angewandten Patch 20180829 nicht zusammenlegen"
Cancelled: qfold may not combine the already applied patch 201829
I'm guessing if you do this, you'll see:
$ hg qapplied 20180829 20180831
which is why it's telling you it can't fold 0831 into 0829 since it's already applied. So just do this:
$ hg qpop
which should leave you here:
$ hg qapplied 20180829
then you can fold in 0831:
$ hg qfold 20180831 $ hg qapplied 20180829
Then if you look at the current patch (hg export tip) it should have everything from both patches in it. You may want to "hg qrefresh -e" to clean up the commit message.
Are you versed in git? If so, the qfold is equivalent to a "rebase -i" where you choose "squash" for the later patch. If not, then ignore this :)
Should I start from sratch and reinstall the complete development environment and then sent in the current version of the complete file as a new patch with reference to #6063 once more?
I assume by "development environment" you mean "clone a new copy of the tree"? You can, if it's easier, but it's probably worth just reading about and understanding what the commands are that you're running for the future :)
--Dan