Unable to Use Jinja Context for "url_param"

[ranggarppb]

A clear and concise description of what the bug is.

Expected results

It gives 'rangga' as the parameter of username in url

Actual results

It returns None

Screenshots

How to reproduce the bug

0. Activate your jinja context in superset/docker/pythonpath_dev/superset_config.py by adding "ENABLE_TEMPLATE_PROCESSING" : True in dictionary of FEATURE_FLAGS
   

1. Go to sqllab

2. Edit your url and add '?username' argument

3. Reload the page

4. Write the query using jinja context of url_param and run the query

Environment

(please complete the following information):

• superset version: 1.0.1 (docker version)
• python version: 3.7.9

Checklist

Make sure to follow these steps before submitting your issue - thank you!

• I have checked the superset logs for python stacktraces and included it here as text if there are any.
• I have reproduced the issue with at least the latest released version of superset.
• I have checked the issue tracker for the same issue and I haven't found one similar.

[robdiciuccio]

Confirmed

[maltoze]

The bug was caused by this PR: #8256

https://github.com/apache/superset/pull/8256/files#diff-adb44dfd0f0ed41256a2b5aa78da261268394042c37c2adbff36775f628ead5aL223