Re: [GSoC] [PATCH v6 3/3] builtin/rebase: support running "git rebase <upstream>"

Now, there is a parallel "rebase-i-in-c" effort going on, and of
course, setting various shell various and formulating a command line
that essentially does 

	. git-rebase--$backend

of course stops working.

+static int run_specific_rebase(struct rebase_options *opts)
+{
+	const char *argv[] = { NULL, NULL };
+ ...
+	switch (opts->type) {
+	case REBASE_AM:
+		backend = "git-rebase--am";
+		backend_func = "git_rebase__am";
+		break;
+	case REBASE_INTERACTIVE:
+		backend = "git-rebase--interactive";
+		backend_func = "git_rebase__interactive";
+		break;
+ ...
+	strbuf_addf(&script_snippet,
+		    ". git-sh-setup && . git-rebase--common &&"
+		    " . %s && %s", backend, backend_func);
+	argv[0] = script_snippet.buf;
+
+	status = run_command_v_opt(argv, RUN_USING_SHELL);