Fix spec path verification with multiple pattern

RSpec.configuration.pattern may not satisfy a glob pattern
if multiple pattern is set (e.g. '**{,/*/**}/*_spec.rb,**/*.feature').

See also RSpec::Core::Configuration#file_glob_from.

lib/guard/rspec_formatter.rb

@@ -77,7 +77,8 @@ def self.spec_path?(path)
       path ||= ""
       path = path.sub(/:\d+\z/, "")
       path = Pathname.new(path).cleanpath.to_s
-      File.fnmatch(pattern, path, flags)
+      stripped = "{#{pattern.gsub(/\s*,\s*/, ',')}}"
+      File.fnmatch(stripped, path, flags)
     end
 
     def dump_summary(*args)

spec/lib/guard/rspec_formatter_spec.rb

@@ -255,5 +255,20 @@ def expected_output(spec_filename)
         end
       end
     end
+
+    context "when RSpec 3.0 is configured to use multiple patterns" do
+      before do
+        allow(::RSpec.configuration).to receive(:pattern).
+          and_return("**{,/*/**}/*_spec.rb,**/*.feature")
+      end
+
+      it "matches a spec file with the first pattern" do
+        expect(described_class.spec_path?('./spec/foo_spec.rb')).to be_truthy
+      end
+
+      it "matches a spec file with the second pattern" do
+        expect(described_class.spec_path?('./spec/acceptance/bar.feature')).to be_truthy
+      end
+    end
   end
 end