How to specify version ranges in install_requires (setuptools, distribute)

According to the documentation, your syntax should work correctly. The documentation states that:

setuptools and pkg_resources use a common syntax for specifying a project’s required dependencies. This syntax consists of a project’s PyPI name, optionally followed by a comma-separated list of “extras” in square brackets, optionally followed by a comma-separated list of version specifiers. A version specifier is one of the operators <, >, <=, >=, == or !=, followed by a version identifier.

The documentation gives a simple example like this:

docutils >= 0.3

# comment lines and \ continuations are allowed in requirement strings
BazSpam ==1.1, ==1.2, ==1.3, ==1.4, ==1.5, \
    ==1.6, ==1.7  # and so are line-end comments

To expand upon that, if you want your package to require a version of docutils greater than version 0.3 but less than version 0.5, code like this would work:

docutils >= 0.3, <=0.5

Two additional notes.

1. The documentation also states that redundant/overlapping dependency specifications will be combined internally, so docutils >= 0.3, >=0.2 would be combined into docutils >= 0.3.
2. Also, be careful about specifying conflicting version numbers, which “is meaningless and may therefore produce bizarre results.” For example, I don’t know why you would, but don’t use this: docutils >= 0.3, <=0.2 since this is impossible.