Migrate an SVN repository (that was previously the merge of 2 repositories) to Git while retaining history


I am trying to migrate an SVN repository that was formerly 2 svn repositories (but within the same svn server, so sharing commit numbers), which was then combined.

So initial state (two repos):

http://svn/mergeTwoProjectsTest/project1/branches/4.0.0
http://svn/mergeTwoProjectsTest/project2/branches/4.0.0

Combined state (1 repo with folders)

http://svn/mergeTwoProjectsTest/branches/4.0.0/project1
http://svn/mergeTwoProjectsTest/branches/4.0.0/project2

The per repo history ends up looking “interesting” but the per file history is preserved in svn (and svn annotate works perfectly).

When attempting to move this to git using git svn git behaves as if these files were first created at the point the 2 repos were combine and loses any history from before then. This is arguably not unreasonable as this is when those files entered the repository, but in git terminology it is perhaps “two forks that forked when no work had been done, remained separate for several years then merged”

Is it possible to migrate an SVN repository that was once 2 SVN repositories to git while maintaining history from before the 2 svn repositories were merged

My problem looks similar to How can I clone an svn repository that changed layouts with git maintaining full history? however my case seems worse, as I have 2 competing repos being combined, rather than just a structure change.