[book] fix Session.{set,free}_cnxset autodoc They're Session methods, not bare functions. Without this building the docs says: reading sources... [ 39%] devrepo/repo/sessions Traceback (most recent call last): File "/usr/lib/pymodules/python2.7/sphinx/ext/autodoc.py", line 326, in import_object obj = self.get_attr(obj, part) File "/usr/lib/pymodules/python2.7/sphinx/ext/autodoc.py", line 232, in get_attr return safe_getattr(obj, name, *defargs) File "/usr/lib/pymodules/python2.7/sphinx/util/inspect.py", line 70, in safe_getattr raise AttributeError(name) AttributeError: set_cnxset Traceback (most recent call last): File "/usr/lib/pymodules/python2.7/sphinx/ext/autodoc.py", line 326, in import_object obj = self.get_attr(obj, part) File "/usr/lib/pymodules/python2.7/sphinx/ext/autodoc.py", line 232, in get_attr return safe_getattr(obj, name, *defargs) File "/usr/lib/pymodules/python2.7/sphinx/util/inspect.py", line 70, in safe_getattr raise AttributeError(name) AttributeError: free_cnxset

missing-dep-for-interpreter make => make | build-essential | dpkg-dev (usr/share/pyshared/cubicweb/skeleton/debian/rules.tmpl)