Re: [PATCH 3/3] git-mergetool--lib: Make vimdiff retain the current directory

David Aguilar [off-list ref] writes:

+resolve_git_prefix() {
+	# If GIT_PREFIX is empty then we cannot use it in tools
+	# that expect to be able to chdir() to its value.
+	if test -z "$GIT_PREFIX"; then
+		GIT_PREFIX=.
+		export GIT_PREFIX
+	fi
+}

Does this "export" have to be conditional?  Otherwise, it would be simpler
to do this upfront at the beginning:

    : GIT_PREFIX=${GIT_PREFIX:-.}