From git-merge Documentation:
By default,
git merge
command refuses to merge histories that do not share a common ancestor. This option can be used to override this safety when merging histories of two projects that started their lives independently. As that is a very rare occasion, no configuration variable to enable this by default exists and will not be added.
I am in that rare occasion frequently, for it is much convenient for my users to download the repo manually, not clone, then after that add the remote and merge. Since the local repo is always news, it is always safe to bypass this on the first pull. Is it possible to set this as default, at least on the first pull? This would be their first time to use any thing technical, so I want them to a GUI software as much as possible. I can setup a script for them to double click.