I have some suggestions to improve the current sequence of hg commands issued by
the Mercurial plugin.

Currently we have:

hg incoming --quiet --bundle hg.bundle --template [blah...] -r $branch
hg pull -u hg.bundle ## ( this command doesn't specify which branch the working
copy should be brought to )

I think this would be better:

hg incoming --quiet --bundle hg.bundle --template [blah...] -r $branch
hg pull hg.bundle ## ( instead of 'hg pull -u hg.bundle' )
hg update -C -r $revision ### ( this command should bring the working copy to
the tip of the specified branch )

On the Java side, instead of

if (branch!=null) args.add("-r",branch);
else args.add("-r", "default");

I suggest this:

if (null == branch || branch.trim().length() == 0)

{ // Excplicitly select the default branch branch = "default"; }

// It's safer to ALWAYS specify which branch to use
args.add("-r", branch);