Thanks for catching this! A few comments.

Blank line here isn't needed.

This check will fail for such versions as 2.0.0 or 1.6.3. We'd need to be more specific in our checks. Since it's going to be a bit longer, I'd recommend creating a utility function that checks if a version is at least the version passed. For example:


def check_version(version, expected):
    return (expected[0] > version[0]) or \
            (expected[0] == version[0] and expected[1] > version[1]) or \
            (expected[0] == version[0] and expected[1] == version[1] and \
             expected[3] >= version[3]))


version and expected should be tuples of (major, minor, micro). It would be good to document that in the function.

Then your check would become:

if not check_version((version_parts.group(1),
                      version_parts.group(2),
                      version_parts.group(2)),
                     (1, 5, 4)):
    die(...)

I'd rather not have the "post-review failed: " prefix here. If we want a prefix to identify failure, we should put it in die(). Maybe just prefix "fatal: "

Please note that not all git releases have a four-part version number.  For instance, my Cygwin installation has plain-old 1.5.4.  You're not using the fourth part anyway, so why not leave that out of the expression?

These need to be >= and not >. Otherwise, if you call:

is_valid_version((1, 2, 3), (1, 2, 3))

It will return False, since 2 is not > 2 and 3 is not > 3.

Looks good.  Committed as r1299.  Thanks!