for_element doesn't work for fragments

[Radu Dan]

When using the for_element property of a label on a tree created from a html fragment that does not contain a body tag, an IndexError is raised:

Traceback (most recent call last):
  File "B:\Workspace\LeadPages\tests\unit\test_parse_form.py", line 9, in setUp
    open("fixtures/input-aweb-form.html").read())
  File "B:\Workspace\LeadPages\leadpages\optins\html.py", line 24, in __init__
    print label.for_element
  File "C:\Program Files (x86)\Python27\lib\site-packages\lxml-3.2.3-py2.7-win32.egg\lxml\html\__init__.py", line 1470, in _for_element__get
    return self.body.get_element_by_id(id)
  File "C:\Program Files (x86)\Python27\lib\site-packages\lxml-3.2.3-py2.7-win32.egg\lxml\html\__init__.py", line 151, in body
    return self.xpath('//body|//x:body', namespaces={'x':XHTML_NAMESPACE})[0]
IndexError: list index out of range

This can be fixed by searching for elements from the fragment root, not the (potentially missing) body tag

Python : sys.version_info(major=2, minor=7, micro=5, releaselevel='final', serial=0)
lxml.etree : (3, 2, 3, 0)
libxml used : (2, 9, 0)
libxml compiled : (2, 9, 0)
libxslt used : (1, 1, 28)
libxslt compiled : (1, 1, 28)

[scoder (scoder)]

Agreed that that would be better. Patches welcome.