Tests: Use TASKDATA env variable in Bash tests

- Now that bash_tap.sh no longer uses subshells, TASKDATA can and
  and should be used.  This fixes a bug introduced with the switch
  to "eval" where having TASKDATA set while running tests would
  potentially lead to problems.

test/bash_tap_tw.sh

@@ -19,8 +19,9 @@ function setup_taskrc {
        fi
     done
 
-    echo 'data.location=.'                 > taskrc
-    echo 'confirmation=off'               >> taskrc
+    export TASKDATA=.
+
+    echo 'confirmation=off'               > taskrc
     echo 'dateformat=m/d/Y'               >> taskrc
     echo 'color.debug=rgb025'             >> taskrc
     echo 'color.header=rgb025'            >> taskrc