setup.py: support Paste 3.0.x In a fresh virtualenv on the stable branch, pastescript 3.0.0 is installed which depends on paste 3.0.x. Using this virtualenv to upgrade to the default branch, using 'pip install --upgrade -e .' fails because on the default branch, the paste version is restricted with '>= 2.0.3, < 3'. Following error occurs: pastescript 3.0.0 has requirement Paste>=3.0, but you'll have paste 2.0.3 which is incompatible. ... Traceback (most recent call last): File "<string>", line 1, in <module> File ".../kallithea/kallithea-release/setup.py", line 160, in <module> """, File "/usr/lib64/python2.7/distutils/core.py", line 151, in setup dist.run_commands() File "/usr/lib64/python2.7/distutils/dist.py", line 953, in run_commands self.run_command(cmd) File "/usr/lib64/python2.7/distutils/dist.py", line 972, in run_command cmd_obj.run() File ".../kallithea/venv/kallithea-release/lib/python2.7/site-packages/setuptools/command/develop.py", line 36, in run self.install_for_development() File ".../kallithea/venv/kallithea-release/lib/python2.7/site-packages/setuptools/command/develop.py", line 117, in install_for_development self.run_command('egg_info') File "/usr/lib64/python2.7/distutils/cmd.py", line 326, in run_command self.distribution.run_command(command) File "/usr/lib64/python2.7/distutils/dist.py", line 972, in run_command cmd_obj.run() File ".../kallithea/venv/kallithea-release/lib/python2.7/site-packages/setuptools/command/egg_info.py", line 270, in run ep.require(installer=installer) File ".../kallithea/venv/kallithea-release/lib/python2.7/site-packages/pkg_resources/__init__.py", line 2307, in require items = working_set.resolve(reqs, env, installer) File ".../kallithea/venv/kallithea-release/lib/python2.7/site-packages/pkg_resources/__init__.py", line 854, in resolve raise VersionConflict(dist, req).with_context(dependent_req) pkg_resources.VersionConflict: (Paste 2.0.3 (.../kallithea/venv/kallithea-release/lib/python2.7/site-packages), Requirement.parse('Paste>=3.0')) The '< 3' restriction is introduced with commit e1ab826131334150b1f003e26de3207c34fc6e67 in January 2017, at which point 2.0.3 was the latest version. Version 3.0.0 was introduced in October 2018. Paste has a new maintainer and moved to github, after years of inactivity (March 2016 -> Oct 2018). There have AFAICS not been incompatible changes. This analysis is based on: - the news file: https://pythonpaste.readthedocs.io/en/latest/news.html - the commit message of the 3.0.0 release: (https://github.com/cdent/paste/commit/9ceef07267ba83ea5c00533f85f9edf9ba38cd71) "This is for the sake of getting something out there, including fixes to get stuff working with Python 3.7." - and a walk through the commits since 2.0.3 on github (https://github.com/cdent/paste/commits/master).