bootstrap_develop.sh does not installs scrypt correctly.

After running the bootstrap, running bitmask gives this exception:

shell> bitmask -dN
Traceback (most recent call last):
  File "/tmp/bitmask/bitmask.venv/bin/bitmask", line 9, in 
    load_entry_point('leap.bitmask==0.3.8-58-g001dfc4', 'console_scripts', 'bitmask')()
  File "/tmp/bitmask/bitmask.venv/local/lib/python2.7/site-packages/pkg_resources.py", line 378, in load_entry_point
    return get_distribution(dist).load_entry_point(group, name)
  File "/tmp/bitmask/bitmask.venv/local/lib/python2.7/site-packages/pkg_resources.py", line 2566, in load_entry_point
    return ep.load()
  File "/tmp/bitmask/bitmask.venv/local/lib/python2.7/site-packages/pkg_resources.py", line 2260, in load
    entry = __import__(self.module_name, globals(),globals(), ['__name__'])
  File "/tmp/bitmask/bitmask_client/src/leap/bitmask/app.py", line 57, in 
    from leap.bitmask.services.mail.repair import repair_account
  File "/tmp/bitmask/bitmask_client/src/leap/bitmask/services/mail/repair.py", line 29, in 
    from leap.bitmask.services.soledad.soledadbootstrapper import get_db_paths
  File "/tmp/bitmask/bitmask_client/src/leap/bitmask/services/soledad/soledadbootstrapper.py", line 44, in 
    from leap.soledad.client import Soledad, BootstrapSequenceError
  File "/tmp/bitmask/soledad/client/src/leap/soledad/client/__init__.py", line 48, in 
    import scrypt
  File "build/bdist.linux-i686/egg/scrypt.py", line 11, in 
ImportError: No module named _scrypt

(from redmine: created on 2014-01-13, closed on 2014-01-13, relates #3812 (closed), relates #5309 (closed))