topic: add tests to demonstrate topic confuses the branchhead checking logic
While topics are in play, we store the branchheads (which has a topic)
in "branchname:topicname" format. After digging into it I found that
even in the case when we should have branch heads for "bname:tname"
we get heads for "bname".
The tests output reflect the confusion in branch head checking logic.
Next patch will be fixing the problem.
Doc is generated with sphinx.
You can generate the doc with:
```
make
```
# Tutorials
For updating the tutorials, you need to have the docgraph extension installed
(https://pypi.python.org/pypi/hg-docgraph).
Then run the test-topic-tutorial.t and test-tutorial.t to update the output if
needed.
You'll need the dot binary (likely installed by the graphviz package in your
package manager) in order to have graphviz graphs rendered in the html output.
Simply run make in the docs directory should takes care of the conversion of
the tutorial .t files into .rst files. Then sphinx should do the rest of the
jobs by rendering graphviz graphs.