* automake.in (require_variables): The fix introduced in 2002-09-19 is imcomplete. Rewrite the conditional variable definition check using &variable_not_always_defined_in_cond. * tests/cond26.test, tests/cond27.test, tests/cond28.test: New file. * tests/Makefile.am (TESTS): Add cond26.test, cond27.test, and cond28.test. Reported by Juergen Keil.