Update

The issue seems to be the failure to uninstall old django-microblogging-0.1.2 from virtualenv in heroku. Tried the method in https://stackoverflow.com/a/9463068/165603 to uninstall the previous version and it seems to work.

In particular the command used was:

heroku config:add BUILDPACK_URL=git@github.com:heroku/heroku-buildpack-python.git#purge

Try to put

django-microblogging-0.2.dev1.tar.gz
# or
path_to/django-microblogging-0.2.dev1.tar.gz

in requirements.txt directly. When you use relative path, it should be relative to the directory inside which you’re running the pip.

Also, you could use

django-microblogging==0.2.dev1