Function to make upstream to "upstream"

bash function

	setupstream = "!f() { \
		local rem=$(git remote | grep -v '^origin$') \
		if [ \"$(wc -l <<<\"$rem\")\" -gt 1 ]; then \
			echo 'Too many remotes.' >&2 \
			return \
		fi \
		if [ -z \"$rem\" ]; then \
			echo 'No non-origin remote found.' >&2 \
			return \
		fi \
		if [ \"$rem\" = upstream ]; then \
			echo '\"upstream\" remote already exists.' \
			return \
		fi \
		git remote rename \"$rem\" upstream \
	}; \
	f"