patch to create a file is applied incorrectly

[kratsg]

I'm not sure how to trivially provide a reproducer for others to clone and run with, but when I created a patch like so

$ cat recipes/histfitter/patches/0003-add-init.py.patch
From faf9fb6712febcc4d868e8c5a7009ea564950cfe Mon Sep 17 00:00:00 2001
From: Giordon Stark <kratsg@gmail.com>
Date: Tue, 31 Mar 2026 22:45:11 -0700
Subject: [PATCH 3/3] add init.py

---
 python/__init__.py | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 python/__init__.py

diff --git a/python/__init__.py b/python/__init__.py
new file mode 100644
index 0000000..0f283b0
--- /dev/null
+++ b/python/__init__.py
@@ -0,0 +1 @@
+# ensure package
--
2.45.2

which creates a python/__init__.py file with the contents of # ensure package alone -- I noticed that rattler-build build --recipe recipe/histfitter -vvv creates ${SRC}/__init__.py instead of ${SRC}/python/__init__.py (wrong directory):

Applying patch: /Users/kratsg/staged-recipes/recipes/histfitter/patches/0003-add-init.py.patch
2026-04-01T06:00:52.275403Z DEBUG Fetching source code: rattler_build::source::patch: Patch will be applied:
	From: None
	To:Some(
    "/Users/kratsg/staged-recipes/output/bld/rattler-build_histfitter_1775023251/work/__init__.py",
)

Is this expected behavior, or a bug? My workaround is to a custom touch python/__init__.py as part of the build in the recipe, instead of relying on it as a patch.

[matthewfeickert]

For additional context: This came up in conda-forge/staged-recipes#32408

[wolfv]

That does sound like a bug ... it's sometimes a little tricky to strip the right amount of directories, and it seems like we're getting it wrong in this case.

[matthewfeickert]

That does sound like a bug

@kratsg Can you open this up as an Issue then? (Unless a member of the rattler-build team wants to convert this Discussion)

[Hofer-Julian]

I created an issue for this: #2399