How to convert to GIT an old SVN repository with trunk/branches created later

I'm trying to migrate a really old SVN repository to GIT maintaining history, but having in mind that the repository didn't have the trunk/branches/tags structure all the time, but instead it was created without them, and the repository was migrated to the trunk/branches/tags structure later.

I've tried with git-svn with the command:

git svn clone <repo_url> --stdlayout

but the problem is that history gets cut on the "trunk, branches and tags created" commit, so everything before that commit is lost. I've also tried with:

git svn clone <repo_url> -T/ -bbranches -ttags

which gets all the commits, but creates a real mesh in the commit graph because it duplicates commits in the branches and the trunk, and does not create any relation between master and branches. I tried cleaning it up with commands like:

git filter-branch -f --index-filter "git rm -rf --cached --ignore-unmatch branches tags" -- --all

which removes the branches folder form the trunk branch mostly right, (and removes a lot of duplicated commits) and also trying to move the trunk folder to the root with:

git filter-branch --tree-filter "if test -d 'trunk'; then  git mv trunk/\* .; fi" --tag-name-filter cat --prune-empty -- --all

but doesn't work. I'm working on windows, so the command in git-svn docs for moving all items is not working for me (missing sed):

git filter-branch --index-filter \
    'git ls-files -s | sed "s-\t\"*-&newsubdir/-" |
        GIT_INDEX_FILE=$GIT_INDEX_FILE.new \
            git update-index --index-info &&
     mv "$GIT_INDEX_FILE.new" "$GIT_INDEX_FILE"' HEAD

(which I rewrote to :)

git filter-branch --index-filter \
    'git ls-files -s | sed "s-\t\"trunk/\(*\)-\1-" |
        GIT_INDEX_FILE=$GIT_INDEX_FILE.new \
            git update-index --index-info &&
    mv "$GIT_INDEX_FILE.new" "$GIT_INDEX_FILE"' HEAD

Any idea if what I'm trying to do is possible or should I just quit and keep history only until creation of trunk/branches/tags?

Solution

I finally found a solution: using svn-all-fast-export (svn2git) I got to create a repository with all the history with the following script:

create repository REPONAME
end repository

# Master branch

match /
  repository REPONAME
  max revision REVISION_BEFORE_TRUNK_BRANCHES_TAGS_CREATION
  branch master
end match

match /trunk/
  repository REPONAME
  branch master
end match

# Common branches

match /branches/([^/]+)/
  repository REPONAME
  branch \1
end match

# Ignore everything else
match /
end match

As I was on windows, had to compile on Windows Substime for Linux, installing "build-essential subversion git qtchooser qt5-default libapr1 libapr1-dev libsvn-dev"; or cygwin with the following libs (as explained in this issue)

gcc-g++ (v7.4.0-1)
libQt5Core-devel (v5.9.4-2)
libapr1 (v1.6.5-1)
libapr1-devel (v1.6.5-1)
make (v4.2.1-2)
subversion (v1.11.1-1)
subversion-devel (v1.11.1-1)