Fix "git-merge -s bogo" help text

It does not make much sense to reuse the output code from "git help" to
show the list of commands to the standard output while giving the error
message before that to the standard error stream.  This makes the output
consistent to that of the 1.6.0 version of "git merge".
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

builtin-merge.c

@@ -110,9 +110,17 @@ static struct strategy *get_strategy(const char *name)
 		}
 	}
 	if (!is_in_cmdlist(&main_cmds, name) && !is_in_cmdlist(&other_cmds, name)) {
-
-		fprintf(stderr, "Could not find merge strategy '%s'.\n\n", name);
-		list_commands("strategies", longest, &main_cmds, &other_cmds);
+		fprintf(stderr, "Could not find merge strategy '%s'.\n", name);
+		fprintf(stderr, "Available strategies are:");
+		for (i = 0; i < main_cmds.cnt; i++)
+			fprintf(stderr, " %s", main_cmds.names[i]->name);
+		fprintf(stderr, ".\n");
+		if (other_cmds.cnt) {
+			fprintf(stderr, "Available custom strategies are:");
+			for (i = 0; i < other_cmds.cnt; i++)
+				fprintf(stderr, " %s", other_cmds.names[i]->name);
+			fprintf(stderr, ".\n");
+		}
 		exit(1);
 	}