[tahoe-lafs-trac-stream] [Tahoe-LAFS] #2876: tox won't run on ubuntu xenial: python3

[Tahoe-LAFS]

#2876: tox won't run on ubuntu xenial: python3
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     Reporter:  warner     |      Owner:  daira
         Type:  defect     |     Status:  new
     Priority:  major      |  Milestone:  1.13.0
    Component:  packaging  |    Version:  1.12.1
   Resolution:             |   Keywords:
Launchpad Bug:             |
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Comment (by warner):

 Ah, part of the issue is py3-incompatible syntax in tahoe's setup.py
 itself, or (worse) in those of the dependencies. When I do a `pip install
 .` inside a py3 virtualenv (so `pip` is really `pip3`), the first
 exception I get is a syntax error in zfec's setup.py, which contains an
 old-style `print "something"` statement.

 Tahoe's setup.py is first called as `setup.py egg-info`, then if this
 succeeds, pip(3) starts doing the same for its dependencies. To deliver a
 useful error message early, we need `egg-info` to throw.

 When `tox` runs, the first thing it does is to run `sdist`. Only later,
 inside the new (py2) virtualenv, does it run `egg_info`. So maybe changing
 the `egg_info` command to check the version, but making sure that `sdist`
 *is* py3-tolerant, would allow tox3 to work and still retain the useful
 error when pip3 is used by mistake.

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Ticket URL: <https://tahoe-lafs.org/trac/tahoe-lafs/ticket/2876#comment:6>
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