microblog: ImportError: No module named migrate.versioning?

After pip install -r requirements.txt and python db_create.py, I still get the following? Which library is it taken from Flask-Migrate, Migrate?

    from migrate.versioning import api
ImportError: No module named migrate.versioning

I did get:

ld: library not found for -lgcc_s.10.5
collect2: ld returned 1 exit status
error: command '/usr/local/bin/gcc-4.2' failed with exit status 1

EDIT: OK it is the sqlalchemy-migrate==0.9.2 not installed, but not sure why pip install -r requirements.txt didnt do it for me?