pip construes "3.0.0-alpha-1" as later than "3.0.0a3"

[nathanielmanistaatgoogle]

Trivially reproducible for me; let me know if you have problems:

(with a virtual environment "venv")
$ venv/bin/pip install --upgrade "protobuf>=3.0.0a3"
Downloading/unpacking protobuf>=3.0.0a3
  Downloading protobuf-3.0.0-alpha-1.tar.gz (193kB): 193kB downloaded

I currently can't write any dependencies as protobuf>=3.0.0a3 and count on them getting the latest version of protobuf from PyPI.

@haberman: I suspect that the right thing to do here is remove the 3.0.0-alpha-1 package, even if doing so breaks some folks - "alpha" does mean "occasional hardship".

[nathanielmanistaatgoogle]

When I look at https://pypi.python.org/pypi/protobuf today I don't see a 3.0.0-alpha-1 package, so it seems to me that this issue is likely resolved. Please close if you agree?

[xfxyjwf]

Yes, we removed (hide) the 3.0.0-alpha-1 package due to the inconsistent naming.

[michael-berlin]

Just as an FYI:

We got bitten by this issue in the wild. Apparently, we've hit a specific combination of software versions in our Travis CI tests where the hidden alpha-1 release is not ignored.

Output from the pip -v command which installs gRPC Python:

Downloading/unpacking protobuf>=3.0.0a3 (from grpcio==0.13.0)
  Ignoring link https://pypi.python.org/packages/source/p/protobuf/protobuf-2.0.0beta.tar.gz#md5=a0bc636064dc618068f63470a873f929 (from https://pypi.python.org/simple/protobuf/), version 2.0.0beta doesn't match >=3.0.0a3
  Ignoring link https://pypi.python.org/packages/source/p/protobuf/protobuf-2.0.3.tar.gz#md5=abe09188aed233ed35e2fc69b3d1a5b0 (from https://pypi.python.org/simple/protobuf/), version 2.0.3 doesn't match >=3.0.0a3
  Ignoring link https://pypi.python.org/packages/source/p/protobuf/protobuf-2.3.0.tar.gz#md5=bb020c962f252fe81bfda8fb433bafdd (from https://pypi.python.org/simple/protobuf/), version 2.3.0 doesn't match >=3.0.0a3
  Ignoring link https://pypi.python.org/packages/source/p/protobuf/protobuf-2.4.1.tar.gz#md5=72f5141d20ab1bcae6b1e00acfb1068a (from https://pypi.python.org/simple/protobuf/), version 2.4.1 doesn't match >=3.0.0a3
  Ignoring link https://pypi.python.org/packages/source/p/protobuf/protobuf-2.5.0.tar.gz#md5=338813f3629d59e9579fed9035ecd457 (from https://pypi.python.org/simple/protobuf/), version 2.5.0 doesn't match >=3.0.0a3
  Ignoring link https://pypi.python.org/packages/source/p/protobuf/protobuf-2.6.0.tar.gz#md5=3a25a1efda4feba5427b96e9b34bc94a (from https://pypi.python.org/simple/protobuf/), version 2.6.0 doesn't match >=3.0.0a3
  Ignoring link https://pypi.python.org/packages/source/p/protobuf/protobuf-2.6.1.tar.gz#md5=6bf843912193f70073db7f22e2ea55e2 (from https://pypi.python.org/simple/protobuf/), version 2.6.1 doesn't match >=3.0.0a3
  Ignoring link https://pypi.python.org/packages/source/p/protobuf/protobuf-3.0.0a2.tar.gz#md5=47fdec5eabfcf6a22622a9febf17d262 (from https://pypi.python.org/simple/protobuf/), version 3.0.0a2 doesn't match >=3.0.0a3
  Using version 3.0.0-alpha-1 (newest of versions: 3.0.0-alpha-1, 3.0.0b2, 3.0.0b1.post2, 3.0.0a3)
  Downloading protobuf-3.0.0-alpha-1.tar.gz (193Kb): 193Kb downloaded
  Running setup.py egg_info for package protobuf

This is supposedly with pip 1.1. Full log: https://travis-ci.org/youtube/vitess/builds/113311581

However, I could not reproduce the issue locally with a pip version 1.1. On other machines, it always ignores the alpha-1 version:

Downloading/unpacking protobuf>=3.0.0a3 (from grpcio==0.13.0)
  Ignoring link https://pypi.python.org/packages/source/p/protobuf/protobuf-2.0.0beta.tar.gz#md5=a0bc636064dc618068f63470a873f929 (from https://pypi.python.org/simple/protobuf/), version 2.0.0beta doesn't match >=3.0.0a3
  Ignoring link https://pypi.python.org/packages/source/p/protobuf/protobuf-2.0.3.tar.gz#md5=abe09188aed233ed35e2fc69b3d1a5b0 (from https://pypi.python.org/simple/protobuf/), version 2.0.3 doesn't match >=3.0.0a3
  Ignoring link https://pypi.python.org/packages/source/p/protobuf/protobuf-2.3.0.tar.gz#md5=bb020c962f252fe81bfda8fb433bafdd (from https://pypi.python.org/simple/protobuf/), version 2.3.0 doesn't match >=3.0.0a3
  Ignoring link https://pypi.python.org/packages/source/p/protobuf/protobuf-2.4.1.tar.gz#md5=72f5141d20ab1bcae6b1e00acfb1068a (from https://pypi.python.org/simple/protobuf/), version 2.4.1 doesn't match >=3.0.0a3
  Ignoring link https://pypi.python.org/packages/source/p/protobuf/protobuf-2.5.0.tar.gz#md5=338813f3629d59e9579fed9035ecd457 (from https://pypi.python.org/simple/protobuf/), version 2.5.0 doesn't match >=3.0.0a3
  Ignoring link https://pypi.python.org/packages/source/p/protobuf/protobuf-2.6.0.tar.gz#md5=3a25a1efda4feba5427b96e9b34bc94a (from https://pypi.python.org/simple/protobuf/), version 2.6.0 doesn't match >=3.0.0a3
  Ignoring link https://pypi.python.org/packages/source/p/protobuf/protobuf-2.6.1.tar.gz#md5=6bf843912193f70073db7f22e2ea55e2 (from https://pypi.python.org/simple/protobuf/), version 2.6.1 doesn't match >=3.0.0a3
  Ignoring link https://pypi.python.org/packages/source/p/protobuf/protobuf-3.0.0-alpha-1.tar.gz#md5=7318fdb3dc43390b305dbc4f0df2aefa (from https://pypi.python.org/simple/protobuf/), version 3.0.0-alpha-1 doesn't match >=3.0.0a3
  Ignoring link https://pypi.python.org/packages/source/p/protobuf/protobuf-3.0.0a2.tar.gz#md5=47fdec5eabfcf6a22622a9febf17d262 (from https://pypi.python.org/simple/protobuf/), version 3.0.0a2 doesn't match >=3.0.0a3
  Using version 3.0.0b2 (newest of versions: 3.0.0b2, 3.0.0b1.post2, 3.0.0a3)
  Downloading protobuf-3.0.0b2.tar.gz (200Kb): 200Kb downloaded
  Running setup.py egg_info for package protobuf

This is just an FYI. I don't understand what's wrong there and gave up debugging it. Instead, I'll work-around the issue by explicitly pinning our gRPC Python copy to protobuf 3.0.0a3.