When cloning a repository with a branch name that contains spaces the polling fails with:

hg parsing error at 4: invalid token

after the "hg log" command getting changelog.

The problem seems related on how hg parses the command line and escaping of the console and hg.
For example:

hg log --rev "branch with spaces"

will work, but:

hg log --rev "branch with spaces" --follow
or:
hg log --follow --rev "branch with spaces"

will not (with the same error reported). A typical "hg log" command generated with mercurial-plugin is like this command (with many other parameters).

The correct command should be something like:

hg log --rev '"branch with spaces"' --follow ...etc...

using single quotes for the console and double quotes for the hg/python parser.