Index: src/main/java/hudson/plugins/mercurial/MercurialSCM.java
===================================================================
--- src/main/java/hudson/plugins/mercurial/MercurialSCM.java	(revision 10725)
+++ src/main/java/hudson/plugins/mercurial/MercurialSCM.java	(working copy)
@@ -26,7 +26,7 @@
 
 /**
  * Mercurial SCM.
- * 
+ *
  * @author Kohsuke Kawaguchi
  */
 public class MercurialSCM extends SCM implements Serializable {
@@ -34,7 +34,7 @@
      * Source repository URL from which we pull.
      */
     private final String source;
-    
+
     /**
      * Prefixes of files within the repository which we're dependent on.
      * Storing as member variable so as to only parse the dependencies string once.
@@ -42,9 +42,9 @@
     private transient final Set<String> _modules = new HashSet<String>();
     // Same thing, but not parsed for jelly.
     private final String modules;
-    
+
     /**
-     * In-repository branch to follow. Null indicates "default". 
+     * In-repository branch to follow. Null indicates "default".
      */
     private final String branch;
 
@@ -62,19 +62,21 @@
             r[i] = r[i].replaceAll("\\\\ ", " ");
 
             // Strip leading slashes
-            while (r[i].startsWith("/"))
+            while (r[i].startsWith("/")) {
                 r[i] = r[i].substring(1);
+            }
 
             // Use unix file path separators
             r[i] = r[i].replace('\\', '/');
         }
 
-        this._modules.addAll(Arrays.asList(r));
+        _modules.addAll(Arrays.asList(r));
 
         // normalization
         branch = Util.fixEmpty(branch);
-        if(branch!=null && branch.equals("default"))
+        if(branch!=null && branch.equals("default")) {
             branch = null;
+        }
         this.branch = branch;
 
         this.browser = browser;
@@ -113,11 +115,16 @@
         tmpTxt.write(FILES_STYLE);
 
         // Get the list of changed files.
+        ArgumentListBuilder args = new ArgumentListBuilder();
+        args.add(getDescriptor().getHgExe(), "incoming", "--style", tmpFile.getCanonicalPath());
+        if (branch != null) {
+            args.add("-r", branch);
+        }
+
         launcher.launch(
-                new String[]{getDescriptor().getHgExe(), "incoming", "--style", tmpFile.getCanonicalPath()},
+                args.toCommandArray(),
                 EnvVars.masterEnvVars, new ForkOutputStream(baos, output), workspace).join();
 
-
         Set<String> changedFileNames = new HashSet<String>();
         parseIncomingOutput(baos, changedFileNames);
 
@@ -182,25 +189,31 @@
     public boolean checkout(AbstractBuild build, Launcher launcher, FilePath workspace, BuildListener listener, File changelogFile) throws IOException, InterruptedException {
         boolean canUpdate = workspace.act(new FileCallable<Boolean>() {
             public Boolean invoke(File ws, VirtualChannel channel) throws IOException {
-                if(!HgRc.getHgRcFile(ws).exists())
+                if(!HgRc.getHgRcFile(ws).exists()) {
                     return false;
+                }
                 HgRc hgrc = new HgRc(ws);
                 return canUpdate(hgrc);
             }
 
             private boolean canUpdate(HgRc ini) {
                 String upstream = ini.getSection("paths").get("default");
-                if(upstream==null)  return false;
+                if(upstream==null) {
+                    return false;
+                }
 
-                if(upstream.equals(source)) return true;
+                if(upstream.equals(source)) {
+                    return true;
+                }
                 return source.startsWith("file:/") && new File(upstream).toURI().toString().equals(source);
             }
         });
 
-        if(canUpdate)
+        if(canUpdate) {
             return update(build,launcher,workspace,listener,changelogFile);
-        else
+        } else {
             return clone(build,launcher,workspace,listener,changelogFile);
+        }
     }
 
     /**
@@ -250,7 +263,9 @@
                 args.add("--debug");
             }
 
-            if(branch!=null)    args.add("-r",branch);
+            if(branch!=null) {
+                args.add("-r",branch);
+            }
 
             ByteArrayOutputStream errorLog = new ByteArrayOutputStream();
 
@@ -276,7 +291,7 @@
         }
 
         // pull
-        if(r==0 && hgBundle.exists())
+        if(r==0 && hgBundle.exists()) {
             // if incoming didn't fetch anything, it will return 1. That was for 0.9.3.
             // in 0.9.4 apparently it returns 0.
             try {
@@ -290,6 +305,7 @@
                 listener.error("Failed to pull");
                 return false;
             }
+        }
 
         hgBundle.delete(); // do not leave it in workspace
 
@@ -310,8 +326,11 @@
 
         ArgumentListBuilder args = new ArgumentListBuilder();
         args.add(getDescriptor().getHgExe(),"clone");
-        if(branch!=null)    args.add("-r",branch);
-        args.add(source,workspace.getRemote());
+        if(branch!=null) {
+            args.add(source + "#" + branch,workspace.getRemote());
+        } else {
+            args.add(source,workspace.getRemote());
+        }
         try {
             if(launcher.launch(args.toCommandArray(),build.getEnvVars(),listener.getLogger(),null).join()!=0) {
                 listener.error("Failed to clone "+source);
@@ -354,6 +373,7 @@
             load();
         }
 
+        @Override
         public String getDisplayName() {
             return "Mercurial";
         }
@@ -362,7 +382,9 @@
          * Path to mercurial executable.
          */
         public String getHgExe() {
-            if(hgExe==null) return "hg";
+            if(hgExe==null) {
+                return "hg";
+            }
             return hgExe;
         }