[dendron] understand and resolve the issues of automatic merges

[oolonek]

See https://github.com/digital-botanical-gardens-initiative/dendron-dbgi/commit/d24da7f6de3e406e1f8422720d49ccf659ecda50 for an example and commit history for additional cases.

Might have to to with the Dendron specific sync mechanisms (https://wiki.dendron.so/notes/6jpib71kvuuqjbq6txyo0qh/) or with VisualStudio git extension.