If you follow the official instructions to install flexget with existing Python 2.6 and python-virtualenv, than you might encounter the following problem:
flexget@host:~$ flexget/bin/flexget
Traceback (most recent call last):
File "flexget/bin/flexget", line 5, in
from pkg_resources import load_entry_point
File "/home/flexget/flexget/lib/python2.6/site-packages/distribute-0.6.10-py2.6.egg/pkg_resources.py", line 2655, in
working_set.require(__requires__)
File "/home/flexget/flexget/lib/python2.6/site-packages/distribute-0.6.10-py2.6.egg/pkg_resources.py", line 648, in require
needed = self.resolve(parse_requirements(requirements))
File "/home/flexget/flexget/lib/python2.6/site-packages/distribute-0.6.10-py2.6.egg/pkg_resources.py", line 546, in resolve
raise DistributionNotFound(req)
pkg_resources.DistributionNotFound: jsonschema>=2.0
At least on my system, there seems to be a jsonschema < 2.0 installed in the system site packages. This can be prevented by altering the initialization of the virtual Python environment as follows:
virtualenv --no-site-packages ~/flexget/