taxi alias throws an exception

[sebastien-roch]

I did a "taxi update" but I still get this exception:
sebastien:~/www/teachcycle|enroll $ taxi alias jlc_ecom_europe_sprint1 1484/278
Traceback (most recent call last):
File "/usr/local/bin/taxi", line 4, in
app.main()
File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/taxi/app.py", line 148, in main
app.run()
File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/taxi/app.py", line 136, in run
action.run()
File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/taxi/commands.py", line 198, in run
self._add_alias(self.alias, self.mapping)
File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/taxi/commands.py", line 221, in _add_alias
project = projects_db.get(project_activity[0])
NameError: global name 'projects_db' is not defined