hg convert failing on a repo with subrepos

[Svein Seldal]

Hi

I'm having a hg repo which I want to run hg convert on. The repo is 
using subrepos with references to repos from hg, svn and git and it has 
largefiles. hg convert fails if .hgsub* is included when running hg 
convert:

     hg convert -s hg tmp.1-hg -d hg tmp.2-hg --filemap file.map --config 
convert.hg.startrev=5

Attempt 1)  With empty file.map, the convertion fails with: "abort: 
data/.hgsubstate.i at 303030303030: no node!"

Attempt 2)  I don't really need the hg subrepos functionality intact, 
but I must retain the revision controlled files in order to recreate the 
specific subrepos manually if needed. I then rename the hgsub files:

     rename .hgsub .old.hgsub
     rename .hgsubstate .old.hgsubstate

Then it fails even earlier, with "abort: unable to convert merge commit 
since target parents do not merge cleanly". The file listed file failing 
has no relationship with .hgsub.

Attempt 3)  If I completely exclude the subrepo files, then it converts 
fine, but then again the information of the subrepos references are 
lost.

     exclude .hgsub
     exclude .hgsubstate

What can I do to fix or debug this issue? hg verify on a checked out 
clone does not complain on the repo, except for some old subrepos that 
aren't available any more. I'm running hg 4.5.3 from Ubuntu 18.04.


Best regards,
Svein