Calling `Pkg.test()` in a workspace changes the `Project.toml`

[nhz2]

Calling Pkg.test() after activating a package environment in a workspace causes strange edits to the package's Project.toml

Possibly related to #4237

Here is the reproducer:

git clone https://github.com/JuliaIO/ChunkCodecs.jl.git
cd ChunkCodecs.jl
julia +1.12 --project=LibSnappy -e 'using Pkg; Pkg.test()'
git diff

diff --git a/LibSnappy/Project.toml b/LibSnappy/Project.toml
index aadeb96..e4ae0fe 100644
--- a/LibSnappy/Project.toml
+++ b/LibSnappy/Project.toml
@@ -1,16 +1,19 @@
 name = "ChunkCodecLibSnappy"
 uuid = "eac87354-86d5-4a5b-ab5f-a6ee56b239b3"
-authors = ["nhz2 <nhz2@cornell.edu>"]
 version = "0.2.1"
+authors = ["nhz2 <nhz2@cornell.edu>"]
+
+[workspace]
+projects = ["test"]
 
 [deps]
 ChunkCodecCore = "0b6fb165-00bc-4d37-ab8b-79f91016dbe1"
 snappy_jll = "fe1e1685-f7be-5f59-ac9f-4ca204017dfd"
 
+[sources]
+ChunkCodecCore = {path = "ChunkCodecCore"}
+
 [compat]
 ChunkCodecCore = "0.5"
-snappy_jll = "1"
 julia = "1.9"
-
-[workspace]
-projects = ["test"]
+snappy_jll = "1"

julia> versioninfo()
Julia Version 1.12.0-rc1
Commit 228edd6610b (2025-07-12 20:11 UTC)
Build Info:
  Official https://julialang.org release
Platform Info:
  OS: Linux (x86_64-linux-gnu)
  CPU: 16 × Intel(R) Core(TM) i7-10700KF CPU @ 3.80GHz
  WORD_SIZE: 64
  LLVM: libLLVM-18.1.7 (ORCJIT, skylake)
  GC: Built with stock GC
Threads: 1 default, 1 interactive, 1 GC (on 16 virtual cores)