distuninstallcheck: fail also when only one file is left installed This change fixes automake bug#9579. * lib/am/distdir.am (distuninstallcheck): Be stricter in ignoring a potential `dir' file created by install-info and left installed. Also, be more careful about "this can't happen" kind of errors. (am__distuninstallcheck_listfiles): New internal helper macro. * tests/distcheck-pr9579.test: New test. * tests/distcheck-override-infodir.test: Likewise. * tests/Makefile.am (TESTS): Add them. * NEWS, THANKS: Update. Report by Nick Bowler.