Updating harvest

[carlosips]

Hello,

I'm trying to update this plugin from 1.1.0 to current version (1.1.4) but I'm getting next error

mod_wsgi (pid=31763): Target WSGI script '/etc/ckan/default/apache.wsgi' cannot be loaded as Python module.
mod_wsgi (pid=31763): Exception occurred processing WSGI script '/etc/ckan/default/apache.wsgi'.
Traceback (most recent call last):
  File "/etc/ckan/default/apache.wsgi", line 9, in <module>
    application = loadapp('config:%s' % config_filepath)
  File "/usr/lib/ckan/default/lib/python2.7/site-packages/paste/deploy/loadwsgi.py", line 247, in loadapp
    return loadobj(APP, uri, name=name, **kw)
  File "/usr/lib/ckan/default/lib/python2.7/site-packages/paste/deploy/loadwsgi.py", line 272, in loadobj
    return context.create()
  File "/usr/lib/ckan/default/lib/python2.7/site-packages/paste/deploy/loadwsgi.py", line 710, in create
    return self.object_type.invoke(self)
  File "/usr/lib/ckan/default/lib/python2.7/site-packages/paste/deploy/loadwsgi.py", line 146, in invoke
    return fix_call(context.object, context.global_conf, **context.local_conf)
  File "/usr/lib/ckan/default/lib/python2.7/site-packages/paste/deploy/util.py", line 55, in fix_call
    val = callable(*args, **kw)
  File "/usr/lib/ckan/default/src/ckan/ckan/config/middleware/__init__.py", line 46, in make_app
    load_environment(conf, app_conf)
  File "/usr/lib/ckan/default/src/ckan/ckan/config/environment.py", line 99, in load_environment
    p.load_all()
  File "/usr/lib/ckan/default/src/ckan/ckan/plugins/core.py", line 139, in load_all
    load(*plugins)
  File "/usr/lib/ckan/default/src/ckan/ckan/plugins/core.py", line 153, in load
    service = _get_service(plugin)
  File "/usr/lib/ckan/default/src/ckan/ckan/plugins/core.py", line 255, in _get_service
    return plugin.load()(name=plugin_name)
  File "/usr/lib/ckan/default/lib/python2.7/site-packages/pkg_resources/__init__.py", line 2324, in load
    return self.resolve()
  File "/usr/lib/ckan/default/lib/python2.7/site-packages/pkg_resources/__init__.py", line 2330, in resolve
    module = __import__(self.module_name, fromlist=['__name__'], level=0)
  File "/usr/lib/ckan/default/src/ckanext-harvest/ckanext/harvest/harvesters/__init__.py", line 2, in <module>
    from ckanext.harvest.harvesters.ckanharvester import CKANHarvester
  File "/usr/lib/ckan/default/src/ckanext-harvest/ckanext/harvest/harvesters/ckanharvester.py", line 5, in <module>
    from urllib3.contrib import pyopenssl
  File "/usr/lib/ckan/default/lib/python2.7/site-packages/urllib3/contrib/pyopenssl.py", line 23, in <module>
    from ndg.httpsclient.ssl_peer_verification import SUBJ_ALT_NAME_SUPPORT
ImportError: No module named ndg.httpsclient.ssl_peer_verification

is there any guide to update harvest plugin?

P.D: Sorry in advance if my error is obvious but I'm very new in python.

P.D.2: I'm trying to update harvest plugin because when I run harvest, it's not updating dataset's license info from rdf source.

EDIT: I'm using ckan version 2.7