[xorcist]

It's a bit of a mystery, especially since the one of the lowest surprise character they could have chosen was a colon, and indeed colon is already used to separate branch and path -- but only where they are one option and not two.

For example:

  git log mybranch myfile.txt

but:

  git show mybranch:myfile.txt

That's indeed one of the things that trip up people when I try to introduce them to the git model. I wish it had been different.

The double dash is normally not needed when it is self evident if a branch or file is referred to. It is only needed when a file no longer exists or a file and a branch exists with the same name. One could easily have imagined the one-argument syntax to be dominant. It would have been a bit awkward in a few situations, but a lot less confusing in others.