Using pyez's remove_namespaces function to strip namespace information

namespace.py

from lxml import etree
from jnpr.junos.jxml import remove_namespaces

# file contains output of 'show interfaces ge-0/0/0.0'
fh = open('router_output2.xml', 'r')
parser = etree.XMLParser(remove_blank_text=True)
tree = etree.parse(fh, parser)
tree = remove_namespaces(tree)

xpath = "//logical-interface/address-family[address-family-name = 'inet']/interface-address/ifa-local"

tree_list = tree.xpath(xpath)

if tree_list:
  print tree_list[0].text.strip()
else:
  print "xpath expression did not match"