@jhein32 The logic is becoming a bit convoluted here, and after double checking I think the right way to update this results in cleaner code. The shift to using double digits for the name of the library with Boost Python bindings was made in Boost 1.67.0, for both Python 2.x & 3.x; see the Python section in https://www.boost.org/users/history/version_1_67_0.html:

The library name now includes the version suffix of the Python version used to compile it.
For example, a variant compiled with Python 2.7 will produce library names boost_python27
and boost_numpy27, etc.

So the logic should become:

if LooseVersion(self.version) >= LooseVersion("1.67.0"):
    suffix = '%s%s' % (pymajorver, pyminorver)
elif LooseVersion(pymajorver) >= LooseVersion('3.0'):
    suffix = pymajorver
else:
    suffix = ''

(this should have been done already in #1424, but there we overlooked that this change was supposed to be made for both Python versions)

I assumed that was checked properly beforehand ...

I didn't, and I suspect @rubendibattista missed it too...

I was worried about backwards compatibility since I did not know if it was just for new stuff or also for some previous versions and I did not tried with Python 3. So I didn't want to mess up with things I did not test.

I think the proposed solution by @boegel looks good. :)

Sorry about the overlook.

@rubendibattista @boegel

Didn't mean to upset and hope I didn't. When I saw the code I assumed there was a reason for it looking as it did. I submitted a revised version (currently testing).