Make git init use SHA-256 if git is invoked as git3, SHA1 if invoked as git2.

Plain git init could fail with a diagnostic: informing to use one of the two aliases or an option.

What people don't want is making git repos SHA-256 by accident and finding out later that they made repos not compatible with older git.

just make SHA1 the default in all cases unless the user specifies otherwise

	▲	kazinator 8 hours ago \| parent [-]
		I agree, but you're not going to sell that argument to a herd which has decided that git hashes are digital certificates which must be replaced with SHA-256, or the sky will fall.