Scenario names cannot start with a keyword

[pedantic-git]

[Please move this to gherkin-ruby if you prefer]

I discovered this by accident, having a scenario called Buttons don't appear, which begins with the keyword But. It looks like all keywords at the start of scenario names cause the parser to fail (on step generation or feature execution). For example:

Feature: Wibble

Scenario: Given a lot of money
  Given I am an example
  When I do example things
  Then I should work

$ ./bin/spinach -g features/wibble.feature
Traceback (most recent call last):
	13: from ./bin/spinach:3:in `<main>'
	12: from ./bin/spinach:3:in `load'
	11: from /usr/src/app/vendor/bundle/ruby/2.5.0/gems/spinach-0.10.1/bin/spinach:15:in `<top (required)>'
	10: from /usr/src/app/vendor/bundle/ruby/2.5.0/gems/spinach-0.10.1/lib/spinach/cli.rb:30:in `run'
	 9: from /usr/src/app/vendor/bundle/ruby/2.5.0/gems/spinach-0.10.1/lib/spinach/runner.rb:61:in `run'
	 8: from /usr/src/app/vendor/bundle/ruby/2.5.0/gems/spinach-0.10.1/lib/spinach/runner.rb:61:in `map'
	 7: from /usr/src/app/vendor/bundle/ruby/2.5.0/gems/spinach-0.10.1/lib/spinach/runner.rb:65:in `block in run'
	 6: from /usr/src/app/vendor/bundle/ruby/2.5.0/gems/spinach-0.10.1/lib/spinach/parser.rb:39:in `parse'
	 5: from /usr/src/app/vendor/bundle/ruby/2.5.0/gems/gherkin-ruby-0.3.2/lib/gherkin_ruby.rb:8:in `parse'
	 4: from gherkin.y:107:in `parse'
	 3: from /usr/src/app/vendor/bundle/ruby/2.5.0/gems/gherkin-ruby-0.3.2/lib/gherkin_ruby/parser/lexer.rb:31:in `scan_str'
	 2: from /usr/local/lib/ruby/2.5.0/racc/parser.rb:259:in `do_parse'
	 1: from /usr/local/lib/ruby/2.5.0/racc/parser.rb:259:in `_racc_do_parse_c'
/usr/local/lib/ruby/2.5.0/racc/parser.rb:528:in `on_error':  (Racc::ParseError)
parse error on value "Given" (GIVEN)

It's easily worked around by renaming the scenario but I thought I'd report it in case it's not a known issue.