There's a good chance that I'm being dense, but the file content matching regular expression steps don't work.

For example:
Scenario: Example
Given a file named "output.txt" with:
"""
1111111
"""
Then the file "output.txt" should contain "1+"

Fails:
Then the file "output.txt" should contain "1+" # 1.8.6-p399/gems/aruba-0.1.9/lib/aruba/cucumber.rb:145
expected "1111111" to match /1+/ (Spec::Expectations::ExpectationNotMetError)
features/counter.feature:25:in `Then the file "output.txt" should contain "1+"'

If I want to match a regular expression, why would I want Aruba to escape the expression I provide?

Would you expect the following scenario to pass?
Scenario: Check file contents
Given a file named "foo" with:
"""
hello world
"""
Then the file "foo" should contain "h.llo world"
And the file "foo" should not contain "HELLO WORLD"