"prepare-agent" should not overwrite property if execution skipped (#486)

diff --git a/org.jacoco.doc/docroot/doc/changes.html b/org.jacoco.doc/docroot/doc/changes.html
index 628dacb..2f7f0c9 100644
--- a/org.jacoco.doc/docroot/doc/changes.html
+++ b/org.jacoco.doc/docroot/doc/changes.html
@@ -30,6 +30,8 @@
       (GitHub <a href="https://github.com/jacoco/jacoco/issues/177">#177</a>).</li>
   <li><code>ExecutionDataWriter.FORMAT_VERSION</code> is not a compile-time constant
       (GitHub <a href="https://github.com/jacoco/jacoco/issues/474">#474</a>).</li>
+  <li>Maven goal "prepare-agent" should not overwrite existing property value if execution was skipped
+      (GitHub <a href="https://github.com/jacoco/jacoco/issues/486">#486</a>).</li>
 </ul>
 
 <h3>API Changes</h3>