fix: preserve branch reference

[nichmor]

Description

Another look at #5187

Fixes #5185

How Has This Been Tested?

AI Disclosure

• This PR contains AI-generated content.
  • I have tested any AI-generated content in my PR.
  • I take responsibility for any AI-generated content in my PR.

Tools: Claude

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added sufficient tests to cover my changes.
• I have verified that changes that would impact the JSON schema have been made in schema/model.py.

[ruben-arts]

This will still not fix the lockfile if it's out of date:

[workspace]
channels = ["conda-forge"]
platforms = ["linux-64", "osx-arm64"]

[dependencies]
python = ">=3.14.2,<3.15"

[pypi-dependencies]
svgdigitizer = {git = "https://github.com/echemdb/svgdigitizer.git"}
ec-tools = {git = "https://github.com/echemdb/ec-tools.git", branch = "main"}

Run pixi install, will create a proper lockfile

# Now remove main
ec-tools = {git = "https://github.com/echemdb/ec-tools.git"}

Run pixi install, will not update the lockfile
Run pixi update, will update the lockfile

# Now add main back
ec-tools = {git = "https://github.com/echemdb/ec-tools.git", branch = "main"}

Run pixi install, will not update the lockfile but does find it not satisfiable. This is the issue!
Run pixi update to update, this shouldn't be required

[ruben-arts]

It doesn't clean up when switching from without main to with main in the spec.

[ruben-arts]

Now it fixes the issue when switching the branch, but there is still some weird behavior when using rev

It always adds the rev for the default branch:

ec-tools = {git = "https://github.com/echemdb/ec-tools.git"}

      - pypi: git+https://github.com/echemdb/ec-tools.git?rev=693f4bef9243d06849cd807e866ed03562d30bb8#693f4bef9243d06849cd807e866ed03562d30bb8

If you change the rev to something else, it will lock that and it will never invalidate:

ec-tools = {git = "https://github.com/echemdb/ec-tools.git", rev = "main"}

pixi install results in:

      - pypi: git+https://github.com/echemdb/ec-tools.git?rev=main#693f4bef9243d06849cd807e866ed03562d30bb8

now removing the rev from the pixi.toml:

ec-tools = {git = "https://github.com/echemdb/ec-tools.git"}

pixi install again the rev=main stays in the lockfile.

      - pypi: git+https://github.com/echemdb/ec-tools.git?rev=main#693f4bef9243d06849cd807e866ed03562d30bb8

[tdejager]

Please fill out the AI section :)

[tdejager]

Can you please comment and resolve rubens suggestions? :)

[nichmor]

tested all use-cases that are mentioned in the PR ( also between rev <-> tag ). Works as expected.