Bug#1010179: haskell-devscripts: DEB_ENABLE_TESTS broken

[Scott Talbert]

Package: haskell-devscripts
Version: 0.16.11
Severity: normal

After the recent port from shell to Perl, Setting DEB_ENABLE_TESTS=yes 
in debian/rules does not cause the tests to be executed during build.  
This error message is seen during builds:

Use of uninitialized value $ENV{"DEB_ENABLE_TESTS"} in string ne at /usr/share/perl5/Debian/Debhelper/Buildsystem/Haskell/Recipes.pm line 671.
	Debian::Debhelper::Buildsystem::Haskell::Recipes::check_recipe() called at -e line 1
DEB_ENABLE_TESTS not set to yes, not running any build-time tests.