python: Move catch_conflicts.py into subdirectory (#23600)

Python does add the script's directory into "sys.path". For the case of
"catch_conflicts.py" this means "/nix/store" is added to "sys.path". This can
result in very long delays if the store contains a lot of entries.

(moved from master commit 76213d102c1eaa91e733b326d9d312b60103d88a)

3 files changed, 17 insertions, 5 deletions

diff --git a/pkgs/development/interpreters/python/catch_conflicts/README.md b/pkgs/development/interpreters/python/catch_conflicts/README.md
new file mode 100644
index 000000000000..d144b80e3385
--- /dev/null
+++ b/pkgs/development/interpreters/python/catch_conflicts/README.md
@@ -0,0 +1,13 @@
+
+
+catch_conflicts.py
+==================
+
+The file catch_conflicts.py is in a subdirectory because, if it isn't, the
+/nix/store/ directory is added to sys.path causing a delay when building.
+
+Pointers:
+
+- https://docs.python.org/3/library/sys.html#sys.path
+
+- https://github.com/NixOS/nixpkgs/pull/23600
diff --git a/pkgs/development/interpreters/python/catch_conflicts.py b/pkgs/development/interpreters/python/catch_conflicts/catch_conflicts.py
index bb82900c65a9..bb82900c65a9 100644
--- a/pkgs/development/interpreters/python/catch_conflicts.py
+++ b/pkgs/development/interpreters/python/catch_conflicts/catch_conflicts.py
diff --git a/pkgs/development/interpreters/python/mk-python-derivation.nix b/pkgs/development/interpreters/python/mk-python-derivation.nix
index f30bd175daac..5d710fcad882 100644
--- a/pkgs/development/interpreters/python/mk-python-derivation.nix
+++ b/pkgs/development/interpreters/python/mk-python-derivation.nix
@@ -79,9 +79,10 @@ python.stdenv.mkDerivation (builtins.removeAttrs attrs ["disabled"] // {
   postFixup = ''
     wrapPythonPrograms
   '' + lib.optionalString catchConflicts ''
-    # check if we have two packages with the same name in closure and fail
-    # this shouldn't happen, something went wrong with dependencies specs
-    ${python.interpreter} ${./catch_conflicts.py}
+    # Check if we have two packages with the same name in the closure and fail.
+    # If this happens, something went wrong with the dependencies specs.
+    # Intentionally kept in a subdirectory, see catch_conflicts/README.md.
+    ${python.interpreter} ${./catch_conflicts}/catch_conflicts.py
   '' + attrs.postFixup or '''';
 
   passthru = {
@@ -98,5 +99,3 @@ python.stdenv.mkDerivation (builtins.removeAttrs attrs ["disabled"] // {
     isBuildPythonPackage = python.meta.platforms;
   };
 })
-
-