inconsistent behaviour between PIP_NO_BINARY and --no-binary

[alexlancaster]

Description

I am trying to use --only-binary together with --no-binary to force pip to use only binaries for all packages, except for one. It works fine when using both options on the command-line, but it does not work in the same way when using the environment variable version of the exact same options. This is needed in cibuildwheel, because environment variables are the only way to influence pip's behaviour (can't use the command-line directly).

Expected behavior

I would expect the behaviour to be identical when used in combination whether command line (--only-binary / --no-binary) or their environment variable equivalents (PIP_ONLY_BINARY / PIP_NO_BINARY) are used.

pip version

24.3.1

Python version

3.13

OS

Linux

How to Reproduce

1. unset all environment variables to make sure we are always setting them explicitly:

    unset PIP_ONLY_BINARY
    unset PIP_NO_BINARY
   

2. if docopt is installed, uninstall it:

   pip uninstall docopt
   

3. purge cache:

   pip cache purge
   

4. run:

   pip install --only-binary=:all: docopt
   

   should get the following (correct) output - the package should refuse to install because it is only distributed as .tar.gz:

   ERROR: Could not find a version that satisfies the requirement docopt (from versions: none)
   ERROR: No matching distribution found for docopt
   

5. run the environment variable equivalent:

   PIP_ONLY_BINARY=:all: pip install  docopt
   

   this should also fail to install:

   ERROR: Could not find a version that satisfies the requirement docopt (from versions: none)
   ERROR: No matching distribution found for docopt
   

6. so far, so good, now add --no-binary to allow docopt as an exception to the general rule:

   pip install --only-binary=:all: --no-binary=docopt docopt
   

   this allows docopt to install correctly:

   Collecting docopt
     Downloading docopt-0.6.2.tar.gz (25 kB)
     Installing build dependencies ... done
     Getting requirements to build wheel ... done
     Preparing metadata (pyproject.toml) ... done
   Building wheels for collected packages: docopt
     Building wheel for docopt (pyproject.toml) ... done
     Created wheel for docopt: filename=docopt-0.6.2-py2.py3-none-any.whl size=13707 sha256=466c7767b94bb0eb7ce11f401db4e92379c9ab2c0341e5bbb27e719f3c108b1d
     Stored in directory: /home/alex/.cache/pip/wheels/0b/1d/03/175286677fb5a1341cc3e4755bf8ec0ed08f3329afd67446b0
   Successfully built docopt
   Installing collected packages: docopt
   Successfully installed docopt-0.6.2
   

7. uninstall docopt :

   pip uninstall docopt` 
   

   get:

   Found existing installation: docopt 0.6.2
   Uninstalling docopt-0.6.2:
     Would remove:
       /home/alex/.conda/envs/py313/lib/python3.13/site-packages/docopt-0.6.2.dist-info/*
      /home/alex/.conda/envs/py313/lib/python3.13/site-packages/docopt.py
   Proceed (Y/n)? y
     Successfully uninstalled docopt-0.6.2
   

8. purge cache:

   pip cache purge
   

9. try again, but using the environment variables:

   PIP_ONLY_BINARY=:all: PIP_NO_BINARY=docopt pip install docopt
   

   this (erroneously) fails, with output:

   ERROR: Could not find a version that satisfies the requirement docopt (from versions: none)
   ERROR: No matching distribution found for docopt
   

10. This should be functionally identical to step 6, but it is not.

Output

output is shown inline, above.

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