Actually run shell tests (#3583)

Two of these used EXPFAIL which, because nothing is interpreting the TAP
output, does not work. So, that functionality is removed, and the
expected-to-fail bits are commented out or removed.

There was a conditional on the filename in `bash_tap.sh` which caused it
to not actually do anything and just run the test as a simple shell
script. That, too, has been removed.

test/tw-2124.test.sh

@@ -7,9 +7,3 @@
 # Filtering for description with a dash works
 task add foo-bar
 task foo-bar list | grep foo-bar
-
-# Filtering for tag with dash does not work right now
-export EXPFAIL=true
-
-task add test +one-two
-task +one-two list