* aclocal.in ($m4_include_rx): Do not recognize `include', and adjust scan_configure_dep and scan_file accordingly. (scan_configure_dep): Do not search white lines. (scan_file): Strip comments from current line after checking for serial, so that aclocal does not trip on `m4_include' macros in comments. Report from Mike Frysinger. * tests/acloca21.test: New file. * tests/Makefile.am (TESTS): Add it.