--- a/mercurial-server/src/jetbrains/buildServer/buildTriggers/vcs/mercurial/MercurialVcsSupport.java	Tue Feb 25 13:11:18 2014 +0100
+++ b/mercurial-server/src/jetbrains/buildServer/buildTriggers/vcs/mercurial/MercurialVcsSupport.java	Tue Feb 25 13:38:48 2014 +0100
@@ -123,7 +123,7 @@
   @NotNull
   public byte[] getContent(@NotNull final String filePath, @NotNull final VcsRoot vcsRoot, @NotNull final String version) throws VcsException {
     ChangeSet cset = new ChangeSet(version);
-    HgVcsRoot root = myHgVcsRootFactory.createHgRoot(vcsRoot);
+    HgVcsRoot root = getHgRoot(vcsRoot);
     syncRepository(root, cset);
     HgRepo repo = createRepo(root);
     File parentDir = repo.cat().files(filePath).atRevision(cset).call();
@@ -138,6 +138,11 @@
   }
 
   @NotNull
+  public HgVcsRoot getHgRoot(@NotNull final VcsRoot vcsRoot) throws VcsException {
+    return myHgVcsRootFactory.createHgRoot(vcsRoot);
+  }
+
+  @NotNull
   public String getName() {
     return Constants.VCS_NAME;
   }
@@ -174,11 +179,12 @@
   }
 
   @NotNull
-  public String describeVcsRoot(final VcsRoot vcsRoot) {
+  public String describeVcsRoot(@NotNull final VcsRoot vcsRoot) {
     return "mercurial: " + vcsRoot.getProperty(Constants.REPOSITORY_PROP);
   }
 
   @Override
+  @NotNull
   public TestConnectionSupport getTestConnectionSupport() {
     return myTestConnection;
   }
@@ -490,7 +496,7 @@
   }
 
   public void syncRepository(@NotNull final VcsRoot root) throws VcsException {
-    syncRepository(myHgVcsRootFactory.createHgRoot(root));
+    syncRepository(getHgRoot(root));
   }
 
   public void syncRepository(@NotNull final HgVcsRoot root) throws VcsException {
@@ -556,7 +562,7 @@
   }
 
   public void buildPatch(@NotNull VcsRoot root, @Nullable String fromVersion, @NotNull String toVersion, @NotNull PatchBuilder builder, @NotNull CheckoutRules checkoutRules) throws IOException, VcsException {
-    HgVcsRoot hgRoot = myHgVcsRootFactory.createHgRoot(root);
+    HgVcsRoot hgRoot = getHgRoot(root);
     buildPatch(hgRoot, fromVersion, toVersion, builder, checkoutRules);
   }
 
@@ -599,11 +605,12 @@
     return myConfig.allowSourceCaching();
   }
 
+  @NotNull
   public String label(@NotNull String label, @NotNull String version, @NotNull VcsRoot root, @NotNull CheckoutRules checkoutRules) throws VcsException {
     File tmpDir = null;
     try {
       tmpDir = createLabelingTmpDir();
-      HgVcsRoot hgRoot = myHgVcsRootFactory.createHgRoot(root);
+      HgVcsRoot hgRoot = getHgRoot(root);
       hgRoot.setCustomWorkingDir(tmpDir);
       syncRepository(hgRoot);
       HgRepo repo = createRepo(hgRoot);

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mercurial-tests/src/jetbrains/buildServer/buildTriggers/vcs/mercurial/ExtensionsTest.java	Tue Feb 25 13:38:48 2014 +0100
@@ -0,0 +1,76 @@
+/*
+ * Copyright 2000-2014 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package jetbrains.buildServer.buildTriggers.vcs.mercurial;
+
+import jetbrains.buildServer.vcs.VcsException;
+import jetbrains.buildServer.vcs.VcsRoot;
+import junit.framework.Assert;
+import org.jetbrains.annotations.NotNull;
+import org.testng.annotations.Test;
+
+import java.io.File;
+import java.io.IOException;
+
+import static jetbrains.buildServer.buildTriggers.vcs.mercurial.MercurialSupportBuilder.mercurialSupport;
+import static jetbrains.buildServer.buildTriggers.vcs.mercurial.ServerPluginConfigBuilder.serverPluginConfig;
+import static jetbrains.buildServer.buildTriggers.vcs.mercurial.VcsRootBuilder.vcsRoot;
+
+/**
+ * Created 25.02.14 13:17
+ *
+ * @author Eugene Petrenko (eugene.petrenko@jetbrains.com)
+ */
+@RequiredHgVersion(min = "2.0.0")
+public class ExtensionsTest extends BaseMercurialTestCase {
+
+  @Test(dataProviderClass = HgVersionConstraint.class, dataProvider = "installedHgVersion")
+  public void test_no_extension(HgVersion _) throws IOException, VcsException {
+    String extension = "HGExtensionThatDoesNotExits";
+
+    try {
+      runWithExtensions(extension);
+      Assert.fail();
+    } catch (VcsException e) {
+      Assert.assertTrue(e.getMessage().contains(extension));
+    }
+  }
+
+  @Test(dataProviderClass = HgVersionConstraint.class, dataProvider = "installedHgVersion")
+  public void test_extension(HgVersion _) throws IOException, VcsException {
+    runWithExtensions("mq", "largefiles");
+  }
+
+  private void runWithExtensions(@NotNull String... extensions) throws IOException, VcsException {
+    ServerPluginConfig config = serverPluginConfig()
+            .cachesDir(myTempFiles.createTempDir())
+            .hgPath(Util.getHgPath())
+            .build();
+
+    final File myRemoteRepository = myTempFiles.createTempDir();
+    Util.copyRepository(new File("mercurial-tests/testData/rep2"), myRemoteRepository);
+
+
+    final MercurialSupportBuilder hgBuilder = mercurialSupport().withConfig(config);
+    final MercurialVcsSupport vcs = hgBuilder.build();
+    final VcsRoot root = vcsRoot().withUrl(myRemoteRepository.getAbsolutePath()).withBranch("default").withExtensions(extensions).build();
+
+    vcs.getCollectChangesPolicy().getCurrentState(root);
+    vcs.getTestConnectionSupport().testConnection(root);
+  }
+
+
+}

--- a/mercurial-tests/src/jetbrains/buildServer/buildTriggers/vcs/mercurial/VcsRootBuilder.java	Tue Feb 25 13:11:18 2014 +0100
+++ b/mercurial-tests/src/jetbrains/buildServer/buildTriggers/vcs/mercurial/VcsRootBuilder.java	Tue Feb 25 13:38:48 2014 +0100
@@ -16,6 +16,7 @@
 
 package jetbrains.buildServer.buildTriggers.vcs.mercurial;
 
+import jetbrains.buildServer.util.StringUtil;
 import jetbrains.buildServer.vcs.SVcsRoot;
 import jetbrains.buildServer.vcs.impl.VcsRootImpl;
 import org.jetbrains.annotations.NotNull;
@@ -30,6 +31,7 @@
  */
 public class VcsRootBuilder {
 
+  private String myExtensions;
   private String myRepository;
   private String myUsername;
   private String myPassword;
@@ -60,6 +62,7 @@
     vcsRoot.addProperty(Constants.DETECT_SUBREPO_CHANGES, String.valueOf(myDetectSubrepoChanges));
     vcsRoot.addProperty(Constants.INCLUDE_SUBREPOS_IN_PATCH, String.valueOf(myIncludeSubreposInPatch));
     vcsRoot.addProperty(Constants.USE_ARCHIVE_FOR_PATCH, String.valueOf(myUseArchiveForPatch));
+    vcsRoot.addProperty(Constants.HG_EXTENSIONS, myExtensions);
     if (myCloneRepositoryTo != null)
       vcsRoot.addProperty(Constants.SERVER_CLONE_PATH_PROP, String.valueOf(myCloneRepositoryTo.getAbsolutePath()));
     vcsRoot.addProperty(Constants.USE_TAGS_AS_BRANCHES, String.valueOf(myTagsAsBranches));
@@ -82,6 +85,7 @@
       allowing(root).getProperty(with(Constants.USER_FOR_TAG)); will(returnValue(myUserForTag));
       allowing(root).getProperty(with(Constants.DETECT_SUBREPO_CHANGES)); will(returnValue(String.valueOf(myDetectSubrepoChanges)));
       allowing(root).getProperty(with(Constants.USE_TAGS_AS_BRANCHES)); will(returnValue(String.valueOf(myTagsAsBranches)));
+      allowing(root).getProperty(with(Constants.HG_EXTENSIONS)); will(returnValue(myExtensions));
     }});
     if (myCloneRepositoryTo != null) {
       context.checking(new Expectations() {{
@@ -97,6 +101,12 @@
     return this;
   }
 
+  @NotNull
+  public VcsRootBuilder withExtensions(@NotNull String... extensions) {
+    myExtensions = StringUtil.join(extensions, "\n");
+    return this;
+  }
+
 
   public VcsRootBuilder withLocalRepository(@NotNull final File repo) {
     return withUrl(repo.getPath()).withCloneRepositoryTo(repo.getParentFile());