Two bugs when working with branches:

1. Hudson thinks there are changes, even when there aren't any.

2. Workspaces are not the proper checkout.

Here are two patches for src/main/java/hudson/plugins/mercurial/MercurialSCM.java:

For issue #1:

// 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();

For issue #2:

• 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()); + }