Merge an SVN subfolder and a git project changes

There is an internal SVN repository on which many changes have been made. This contains not only the project of interest, but also many other folders.

There is an external git repository, on which many changes have now been applied.

What is the best way to merge these 2 sets of changes.

I was thinking, take the diff of the git HEAD and svn latest changes and manually edit it to make it a p开发者_如何学运维atch. Is there a simpler/better alternative?

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If they share a common ancestor it may be better to merge the changes a revision at a time, picking from either repo in chronological order.

That would be fairly tedious though for large numbers of revisions.