uv pip-compile upgrade dependencies from tool.uv.sources even without the --upgrade flag

[Corentin-Bravo]

• Version of uv : 0.5.15
• OS: Ubuntu 22.04.4 LTS
• Command ran: uv pip compile pyproject.toml --no-emit-index-url --python-platform=linux --output-file=requirements.txt
• (reduced and curated) Content of my pyproject.toml:

dependencies = [
  "myPrivateLibrary_1~=84.0,>=84.0.1",
  "myPrivateLibrary_2~=6.3,>=6.3.3",
]
[[tool.uv.index]]
name = "myIndex"
url = "myIndexUrl"

[tool.uv.sources]
myPrivateLibrary_1 = {index = "myIndex"}
myPrivateLibrary_2 = {index = "myIndex"}

• Original content of my requirements.txt:

myPrivateLibrary_2==6.4.1
    # via myProject (pyproject.toml)
myPrivateLibrary_1==84.0.0
    # via myProject (pyproject.toml)

• Expected content of my requirements.txt after running the command:

myPrivateLibrary_2==6.4.1
    # via myProject (pyproject.toml)
myPrivateLibrary_1==84.0.1
    # via myProject (pyproject.toml)

• Actual content of my requirements.txt after running the command:

myPrivateLibrary_2==6.5.0
    # via myProject (pyproject.toml)
myPrivateLibrary_1==84.0.1
    # via myProject (pyproject.toml)

Note that removing the tool.uv.sources part of the pyproject.toml and running the same command produce the expected behaviour.

It seems as though I ran with the --upgrade-package flag on all packages in tool.uv.sources, which does not seem to be documented, intended or logical from an end user point of view.

If the observed behaviour is intended for your side, is there a way to circumvent it (other than removing the tool.uv.sources block, as I want to make use of the "explicit" index feature) ? Could you document this behaviour, or point me towards the relevant documentation if it exists ?

Thank you in advance