pip understand @# as empty tag/href in git source and breaks installation

[jsenin]

Environment

• pip version: 19.3.1
• Python version: python 3.7.3
• OS: Debian 10 (buster) linux kernel 4.19.0-6-amd64

Description

When a git url contains a '@#' becomes an empty tag or href, that does not match with any fetched refs or tags and produces a : " fatal: ambiguous argument '': unknown revision or path not in the working tree."

When running into requirements.txt, breaks installation at this repo point

Expected behavior

Ignore the empty tag/href and continues

How to Reproduce

1. Setup requirements.txt with a source having a '@#' . e.g:
   -e git+https://github.com/AlexIoannides/py-package-template.git@#egg=py_pkg

2. Then run 'pip install -r requirements.txt'. Installations works

3. Then run install again and you get the error ... an error occurs
   fatal: ambiguous argument '': unknown revision or path not in the working tree.

cat requirements.txt 
-e git+https://github.com/AlexIoannides/py-package-template.git@#egg=py_pkg

(j2f) jorge@debian:~/projects/personal/j2f $ pip install -r requirements.txt 
Obtaining py_pkg from git+https://github.com/AlexIoannides/py-package-template.git@#egg=py_pkg (from -r requirements.txt (line 1))
  Cloning https://github.com/AlexIoannides/py-package-template.git to /home/jorge/.virtualenvs/j2f/src/py-pkg
  Running command git clone -q https://github.com/AlexIoannides/py-package-template.git /home/jorge/.virtualenvs/j2f/src/py-pkg
  WARNING: Generating metadata for package py-pkg produced metadata for project name py-package-template. Fix your #egg=py-pkg fragments.
Collecting numpy
  Downloading https://files.pythonhosted.org/packages/9b/af/4fc72f9d38e43b092e91e5b8cb9956d25b2e3ff8c75aed95df5569e4734e/numpy-1.17.4-cp37-cp37m-manylinux1_x86_64.whl (20.0MB)
     |████████████████████████████████| 20.0MB 6.6MB/s 
Collecting requests
  Using cached https://files.pythonhosted.org/packages/51/bd/23c926cd341ea6b7dd0b2a00aba99ae0f828be89d72b2190f27c11d4b7fb/requests-2.22.0-py2.py3-none-any.whl
Collecting idna<2.9,>=2.5
  Using cached https://files.pythonhosted.org/packages/14/2c/cd551d81dbe15200be1cf41cd03869a46fe7226e7450af7a6545bfc474c9/idna-2.8-py2.py3-none-any.whl
Collecting urllib3!=1.25.0,!=1.25.1,<1.26,>=1.21.1
  Using cached https://files.pythonhosted.org/packages/b4/40/a9837291310ee1ccc242ceb6ebfd9eb21539649f193a7c8c86ba15b98539/urllib3-1.25.7-py2.py3-none-any.whl
Collecting certifi>=2017.4.17
  Using cached https://files.pythonhosted.org/packages/18/b0/8146a4f8dd402f60744fa380bc73ca47303cccf8b9190fd16a827281eac2/certifi-2019.9.11-py2.py3-none-any.whl
Collecting chardet<3.1.0,>=3.0.2
  Using cached https://files.pythonhosted.org/packages/bc/a9/01ffebfb562e4274b6487b4bb1ddec7ca55ec7510b22e4c51f14098443b8/chardet-3.0.4-py2.py3-none-any.whl
Installing collected packages: numpy, idna, urllib3, certifi, chardet, requests, py-package-template
  Running setup.py develop for py-package-template
Successfully installed certifi-2019.9.11 chardet-3.0.4 idna-2.8 numpy-1.17.4 py-package-template requests-2.22.0 urllib3-1.25.7

(j2f) jorge@debian:~/projects/personal/j2f $ pip install -r requirements.txt 
Obtaining py_pkg from git+https://github.com/AlexIoannides/py-package-template.git@#egg=py_pkg (from -r requirements.txt (line 1))
  Updating /home/jorge/.virtualenvs/j2f/src/py-pkg clone
  Running command git fetch -q --tags
  WARNING: Did not find branch or tag '', assuming revision or ref.
  Running command git reset --hard -q ''
  fatal: ambiguous argument '': unknown revision or path not in the working tree.
  Use '--' to separate paths from revisions, like this:
  'git <command> [<revision>...] -- [<file>...]'
ERROR: Command errored out with exit status 128: git reset --hard -q '' Check the logs for full command output.

[uranusjr]

But why would the URL have such a combination? I feel the current behaviour is quite reasonable, and it’s up to the user to fix the URL.

[jsenin]

But why would the URL have such a combination?

Due a human mistake

I feel the current behaviour is quite reasonable, and it’s up to the user to fix the URL.

Well, it could be repaired by the user, but the user must know what is happening. The output message is very confusing.

[chrahunt]

Hi @jsenin, thanks for bringing this up.

If the revision part of the URL is empty then instead of continuing we could abort with an error message like:

The URL git+https://github.com/AlexIoannides/py-package-template.git@#egg=py_pkg (from requirements.txt) has an empty revision (after @) which is not supported. Include a revision after @ or remove @ from the URL.

Is that what you're looking for?

[jsenin]

Yes, this could help a lot El 27 de noviembre de 2019 2:11:44 CET, Christopher Hunt <notifications@github.com> escribió:

…

Hi @jsenin, thanks for bringing this up. If the revision part of the URL is empty then instead of continuing we could abort with an error message like: > The URL `git+https://github.com/AlexIoannides/py-package-template.git@#egg=py_pkg` (from requirements.txt) has an empty revision (after `@`) which is not supported. Include a revision after `@` or remove `@` from the URL. Is that what you're looking for? -- You are receiving this because you were mentioned. Reply to this email directly or view it on GitHub: #7402 (comment)

-- Enviado desde mi dispositivo Android con K-9 Mail. Por favor, disculpa mi brevedad.

[deveshks]

Hi @pradyunsg , @chrahunt ,

I have raised a PR for the same (#7927). Please have a look :)