--- ./build/parseSpec.c.orig	2019-10-02 12:38:51.836127743 +0000
+++ ./build/parseSpec.c	2019-10-02 12:52:33.818447657 +0000
@@ -926,7 +926,22 @@ static rpmSpec parseSpec(const char *spe
 					  &(spec->buildrequires));
 	    break;
 	case PART_BUILD:
-	    parsePart = parseSimpleScript(spec, "%build", &(spec->build));
+	    if (spec->build) {
+		rpmlog(RPMLOG_ERR, _("line %d: second %s\n"), spec->lineNum, "%build");
+		parsePart = PART_ERROR;
+		break;
+	    }
+	    spec->build = newStringBuf();
+	    appendLineStringBuf(spec->build,
+		"ref=/usr/lib/rpm; testarch=$(uname -m)\n"
+		"for s in guess sub; do\n"
+		"    for c in $(find -maxdepth 8 -name \"config.$s\"); do\n"
+		"         grep -q config-patches@ $c || continue\n"
+		"         grep -q \"$testarch[-: ]\" $c || install -m 755 $ref/config.$s $c\n"
+		"     done\n"
+		"done\n"
+	    );
+	    parsePart = parseLines(spec, STRIP_NOTHING, NULL, &(spec->build));
 	    break;
 	case PART_INSTALL:
 	    parsePart = parseSimpleScript(spec, "%install", &(spec->install));