I am using hg version 1.0.2 and plugin 1.11. It seems that support for branches
is completely broken.

1. In workspace I have default branch even if I specify another in project
settings (I check it by hg branch command)
2. On the build start Hudson executes the command hg incoming with parameter -r
name_of_branch. But it is wrong a branch is not a revision and I never have a
revision with such name.

So I did the following to setup the build on mercurial branch:

in workspace:
execute "hg update name_of_branch" to switch workspace to the my branch
in Hudson settings:
clear the branch field - so Hudson now execute hg incoming with out parameter -r
which is more correct.