page_url template tag fails silently when put in a custom inclusion tag

Reproduction

I have defined an inclusion tag and registered it like so (example):

from django.template import Library
@register.inclusion_tag('/path/to/template.html', takes_context=True)
def my_tag(context):
    return {'foo': 'bar'}

The file /path/to/template.html contains:

{% load cms_tags %}
<span>{% page_url "PAGENAME" %}</span>

I use both the custom tag and ordinary reference to page_url in the main cms template:

{% load my_tags cms_tags %}

<h1>{% page_url "PAGENAME" %}</h1>
{% my_tag %}

Expected output:

<h1>/url/to/page<h1>
<span>/url/to/page</span>

Actual output:

<h1>/url/to/page<h1>
<span></span>

Perhaps I am missing something in the tag registration…

Configuration

Virtualenv:

cmsplugin-newsplus==0.1.10
decorator==4.0.4
dj-database-url==0.3.0
Django==1.8.4
django-bower==5.0.4
django-classy-tags==0.6.2
django-cms==3.1.3
django-filebrowser-no-grappelli==3.6.1
django-reversion==1.9.3
django-sekizai==0.8.2
Django-Select2==4.3.1
django-templatetag-handlebars==1.3.0
django-treebeard==3.0
djangocms-admin-style==0.2.8
djangocms-column==1.5
djangocms-file==0.1
djangocms-flash==0.2.0
djangocms-googlemap==0.3
djangocms-inherit==0.1
djangocms-installer==0.8.0
djangocms-link==1.7.1
djangocms-picture==0.1
djangocms-style==1.5
djangocms-teaser==0.1
djangocms-text-ckeditor==2.8.0
djangocms-video==0.1
emencia-django-slideshows==0.9.4
html5lib==0.9999999
ipython==4.0.1
ipython-genutils==0.1.0
path.py==8.1.2
pexpect==4.0.1
pickleshare==0.5
Pillow==2.9.0
ptyprocess==0.5
pytz==2015.4
simplegeneric==0.8.1
six==1.9.0
traitlets==4.0.0
tzlocal==1.2
yolk==0.4.3

[yakky]

@lukasz-virtualo there is a error in you templatetag. It should be :

@register.inclusion_tag('/path/to/template.html', takes_context=True)
def my_tag(context):
    context.update({'foo': 'bar'})
    return context

By doing return {'foo': 'bar'} you are replacing the main context (with the data from page_url) with a custom context containing only foo (or foo and context) in the second example

[lukasz-virtualo]

Thanks. Silly me.