How to select group nodes by substring in xslt

I have this source xml

<TestRun>
  <Results>
    <UnitTestResult testId="1f32f6b9-6623-1321-32b5-b2e84ef44f61" testName="TestMethod1" outcome="Passed">
      <Output>
        <TextMessages>
          <Message>__OWNER__='Team-2'</Message>
        </TextMessages>
      </Output>
    </UnitTestResult>
    <UnitTestResult testId="1f32f6b9-6623-1321-32b5-b2e84ef44f62" testName="TestMethod2" outcome="Failed">
      <Output>
        <TextMessages>
          <Message>__OWNER__='Team-1'</Message>
        </TextMessages>
      </Output>
    </UnitTestResult>
    <UnitTestResult testId="1f32f6b9-6623-1321-32b5-b2e84ef44f63" testName="TestMethod3" outcome="Failed">
      <Output>
        <TextMessages>
          <Message>__OWNER__='Team-1'</Message>
        </TextMessages>
      </Output>
    </UnitTestResult>
    <UnitTestResult testId="1f32f6b9-6623-1321-32b5-b2e84ef44f64" testName="TestMethod4" outcome="Failed">
      <Output>
        <TextMessages>
          <Message>__OWNER__='Team-2'</Message>
        </TextMessages>
      </Output>
    </UnitTestResult>
  </Results>
</TestRun>

And I need to group failed tests by owner which is a substring of Message node.

So the outcome should be

<TestResults>
  <Owner name="Team-1">
    <TestMethod name="TestMethod2"/>
    <TestMethod name="TestMethod3"/>
  </Owner>
  <Owner name="Team-2">
    <TestMethod name="TestMethod4"/>
  </Owner>

Any ideas how to achieve this (using XSLT 1.0 preferably)?