Otherwise we may accidentally update a lock when we shouldn't.
Fixes#12445.
(cherry picked from commit 5c552b62fc)
# Conflicts:
# src/libflake/flake/flake.cc
E.g. in a derivation attribute `foo = ./bar`, if ./bar is a symlink,
we should copy the symlink to the store, not its target. This restores
the behaviour of Nix <= 2.19.
(cherry picked from commit 26b87e78b5)
This seems to be the way to do it now, even though I can't run them
without setting at least one env var.
I'll only fix shellcheck for now. Don't shoot the messenger.
It isn't quite clear to me why the previous commit masked this problem,
but I'm glad shellcheck has an effect or more effect now.
Note that this is just a script that is meant to run outside a
derivation (but also can be called by a derivation builder).
`touch $out` does not belong in it.
`touch $out` worked accidentally in the derivation-based check,
and also in the dev shell, but if pre-commit is invoked without
the dev shell it would fail.
If we previously fetched by revision, the output of "git ls-remote"
won't start with the expected line like
ref: refs/heads/master HEAD
but will be something like
5c4410e3b9891c05ab40d723de78c6f0be45ad30 refs/heads/5c4410e3b9891c05ab40d723de78c6f0be45ad30
This then causes Nix to treat that revision as a refname, which then
leads to warnings like
warning: could not update cached head '5c4410e3b9891c05ab40d723de78c6f0be45ad30' for 'file:///tmp/repo'
(cherry picked from commit c8b22643ba)
This causes Git to create a local ref named refs/head/<rev>, e.g.
$ git -C ~/.cache/nix/gitv3/11irpim06vj4h6c0w8yls6kx4hvl0qd0gr1fvk47n76g6wf1s1vk ls-remote --symref .
5c4410e3b9891c05ab40d723de78c6f0be45ad30 refs/heads/5c4410e3b9891c05ab40d723de78c6f0be45ad30
7f6bde8a20de4cccc2256f088bc5af9dbe38881d refs/heads/7f6bde8a20de4cccc2256f088bc5af9dbe38881d
which confuses readHead(), leading to errors like
fatal: Refusing to point HEAD outside of refs/
warning: could not update cached head 'd275d93aa0bb8a004939b2f1e87f559f989453be' for 'file:///tmp/repo'
(cherry picked from commit ee9fa0d360)
