The s6-linux-init-common package has a FIFO which breaks with this.
--- apk-tools-v2.12.0/src/database.c.old	2020-12-30 02:39:04.000000000 +0000
+++ apk-tools-v2.12.0/src/database.c	2021-01-27 01:47:04.680712750 +0000
@@ -2592,7 +2592,6 @@
 				apk_warning(PKG_VER_FMT": support for packages without embedded "
 					    "checksums will be dropped in apk-tools 3.",
 					    PKG_VER_PRINTF(pkg));
-				ipkg->broken_files = 1;
 				ctx->missing_checksum = 1;
 			}
 			break;