Fix build coverage regex.

Added a spec for regex captures as well.

Fixes #2644

app/models/ci/build.rb

@@ -170,7 +170,8 @@ module Ci
     def extract_coverage(text, regex)
       begin
-        matches = regex.match(text).to_a.last
+        matches = text.scan(Regexp.new(regex)).last
+        matches = matches.last if matches.kind_of?(Array)
         coverage = matches.gsub(/\d+(\.\d+)?/).first
         if coverage.present?

spec/models/build_spec.rb

@@ -189,6 +189,12 @@ describe Ci::Build, models: true do
       it { is_expected.to eq(98.29) }
     end
+
+    context 'using a regex capture' do
+      subject { build.extract_coverage('TOTAL      9926   3489    65%', 'TOTAL\s+\d+\s+\d+\s+(\d{1,3}\%)') }
+
+      it { is_expected.to eq(65) }
+    end
   end
   describe :variables do