1diff -aruN a/bin/automake.in b/bin/automake.in 2--- a/bin/automake.in 2013-11-02 17:48:13.000000000 -0700 3+++ b/bin/automake.in 2018-09-14 10:21:04.000000000 -0700 4@@ -3872,7 +3872,7 @@ 5 sub substitute_ac_subst_variables 6 { 7 my ($text) = @_; 8- $text =~ s/\${([^ \t=:+{}]+)}/substitute_ac_subst_variables_worker ($1)/ge; 9+ $text =~ s/\$[{]([^ \t=:+{}]+)}/substitute_ac_subst_variables_worker ($1)/ge; 10 return $text; 11 } 12 13