cmd: redirect empty about/ to homepage or summary

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

cmd.c

@@ -47,8 +47,17 @@ static void about_fn(void)
 			cgit_redirect(redirect, true);
 			free(currenturl);
 			free(redirect);
-		} else
+		} else if (ctx.repo->readme.nr)
 			cgit_print_repo_readme(ctx.qry.path);
+		else if (ctx.repo->homepage)
+			cgit_redirect(ctx.repo->homepage, false);
+		else {
+			char *currenturl = cgit_currenturl();
+			char *redirect = fmtalloc("%s../", currenturl);
+			cgit_redirect(redirect, false);
+			free(currenturl);
+			free(redirect);
+		}
 	} else
 		cgit_print_site_readme();
 }