patch 7.4.1552
Problem:    ":colorscheme" does not use 'packpath'.
Solution:   Also use in "start" and "opt" directories in 'packpath'.
diff --git a/src/digraph.c b/src/digraph.c
index 5dab51b..b17340c 100644
--- a/src/digraph.c
+++ b/src/digraph.c
@@ -2320,13 +2320,13 @@
 	/* try finding "keymap/'keymap'_'encoding'.vim"  in 'runtimepath' */
 	vim_snprintf((char *)buf, buflen, "keymap/%s_%s.vim",
 						   curbuf->b_p_keymap, p_enc);
-	if (source_runtime(buf, FALSE) == FAIL)
+	if (source_runtime(buf, 0) == FAIL)
 # endif
 	{
 	    /* try finding "keymap/'keymap'.vim" in 'runtimepath'  */
 	    vim_snprintf((char *)buf, buflen, "keymap/%s.vim",
 							  curbuf->b_p_keymap);
-	    if (source_runtime(buf, FALSE) == FAIL)
+	    if (source_runtime(buf, 0) == FAIL)
 	    {
 		vim_free(buf);
 		return (char_u *)N_("E544: Keymap file not found");