Products.CMFCore.DynamicType.icon buggy reliance on length of portal_url

[Darryl Dixon]

This commit:
http://svn.zope.org/Products.CMFCore/trunk/Products/CMFCore/DynamicType.py?rev=105763&r1=105607&r2=105763

Introduced an implicit assumption about the length of portal_url which is not necessarily always true - it assumes both that it is non-zero length and that it does not include "/" at the end of itself. This line is the problematic one:
icon = icon[len(portal_url)+1:]

In order to make this line safe, the code just needs to by slightly more defensive; it needs:
a) to test for non-zero portal_url, and
b) to test that portal_url does *not* end with "/"

Otherwise, this method may return values like:
"ocument_icon.png"

[Darryl Dixon (esrever-otua)]

An example of a working version of the affected function would be:

def icon(self, relative_to_portal=0):
    """
    Using this method allows the content class
    creator to grab icons on the fly instead of using a fixed
    attribute on the class.
    """
    utool = getToolByName(self, 'portal_url')
    portal_url = utool()
    icon = self.getIconURL()
    if portal_url:
        if icon.startswith(portal_url):
            icon = icon[len(portal_url):]
            while icon.startswith('/'):
                icon = icon[1:]
            if not relative_to_portal:
                # Relative to REQUEST['BASEPATH1']
                icon = '%s/%s' % (utool(relative=1), icon)
    return icon