Fix flaky test in build.rs (#8250)

## Summary

Closes #8241.

Author: charliermarsh

crates/uv/tests/it/build.rs

@@ -1835,6 +1835,9 @@ fn tool_uv_sources() -> Result<()> {
         ",
     })?;
 
+    project.child("src").child("__init__.py").touch()?;
+    project.child("README").touch()?;
+
     uv_snapshot!(filters, context.build().current_dir(project.path()), @r###"
     success: true
     exit_code: 0
@@ -1843,63 +1846,73 @@ fn tool_uv_sources() -> Result<()> {
     ----- stderr -----
     Building source distribution...
     running egg_info
-    creating project.egg-info
-    writing project.egg-info/PKG-INFO
-    writing dependency_links to project.egg-info/dependency_links.txt
-    writing requirements to project.egg-info/requires.txt
-    writing top-level names to project.egg-info/top_level.txt
-    writing manifest file 'project.egg-info/SOURCES.txt'
-    reading manifest file 'project.egg-info/SOURCES.txt'
-    writing manifest file 'project.egg-info/SOURCES.txt'
+    creating src/project.egg-info
+    writing src/project.egg-info/PKG-INFO
+    writing dependency_links to src/project.egg-info/dependency_links.txt
+    writing requirements to src/project.egg-info/requires.txt
+    writing top-level names to src/project.egg-info/top_level.txt
+    writing manifest file 'src/project.egg-info/SOURCES.txt'
+    reading manifest file 'src/project.egg-info/SOURCES.txt'
+    writing manifest file 'src/project.egg-info/SOURCES.txt'
     running sdist
     running egg_info
-    writing project.egg-info/PKG-INFO
-    writing dependency_links to project.egg-info/dependency_links.txt
-    writing requirements to project.egg-info/requires.txt
-    writing top-level names to project.egg-info/top_level.txt
-    reading manifest file 'project.egg-info/SOURCES.txt'
-    writing manifest file 'project.egg-info/SOURCES.txt'
-    warning: sdist: standard file not found: should have one of README, README.rst, README.txt, README.md
-
+    writing src/project.egg-info/PKG-INFO
+    writing dependency_links to src/project.egg-info/dependency_links.txt
+    writing requirements to src/project.egg-info/requires.txt
+    writing top-level names to src/project.egg-info/top_level.txt
+    reading manifest file 'src/project.egg-info/SOURCES.txt'
+    writing manifest file 'src/project.egg-info/SOURCES.txt'
     running check
     creating project-0.1.0
-    creating project-0.1.0/project.egg-info
+    creating project-0.1.0/src
+    creating project-0.1.0/src/project.egg-info
     copying files to project-0.1.0...
+    copying README -> project-0.1.0
     copying pyproject.toml -> project-0.1.0
     copying setup.py -> project-0.1.0
-    copying project.egg-info/PKG-INFO -> project-0.1.0/project.egg-info
-    copying project.egg-info/SOURCES.txt -> project-0.1.0/project.egg-info
-    copying project.egg-info/dependency_links.txt -> project-0.1.0/project.egg-info
-    copying project.egg-info/requires.txt -> project-0.1.0/project.egg-info
-    copying project.egg-info/top_level.txt -> project-0.1.0/project.egg-info
-    copying project.egg-info/SOURCES.txt -> project-0.1.0/project.egg-info
+    copying src/__init__.py -> project-0.1.0/src
+    copying src/project.egg-info/PKG-INFO -> project-0.1.0/src/project.egg-info
+    copying src/project.egg-info/SOURCES.txt -> project-0.1.0/src/project.egg-info
+    copying src/project.egg-info/dependency_links.txt -> project-0.1.0/src/project.egg-info
+    copying src/project.egg-info/requires.txt -> project-0.1.0/src/project.egg-info
+    copying src/project.egg-info/top_level.txt -> project-0.1.0/src/project.egg-info
+    copying src/project.egg-info/SOURCES.txt -> project-0.1.0/src/project.egg-info
     Writing project-0.1.0/setup.cfg
     Creating tar archive
     removing 'project-0.1.0' (and everything under it)
     Building wheel from source distribution...
     running egg_info
-    writing project.egg-info/PKG-INFO
-    writing dependency_links to project.egg-info/dependency_links.txt
-    writing requirements to project.egg-info/requires.txt
-    writing top-level names to project.egg-info/top_level.txt
-    reading manifest file 'project.egg-info/SOURCES.txt'
-    writing manifest file 'project.egg-info/SOURCES.txt'
+    writing src/project.egg-info/PKG-INFO
+    writing dependency_links to src/project.egg-info/dependency_links.txt
+    writing requirements to src/project.egg-info/requires.txt
+    writing top-level names to src/project.egg-info/top_level.txt
+    reading manifest file 'src/project.egg-info/SOURCES.txt'
+    writing manifest file 'src/project.egg-info/SOURCES.txt'
     running bdist_wheel
     running build
+    running build_py
+    creating build
+    creating build/lib
+    copying src/__init__.py -> build/lib
+    running egg_info
+    writing src/project.egg-info/PKG-INFO
+    writing dependency_links to src/project.egg-info/dependency_links.txt
+    writing requirements to src/project.egg-info/requires.txt
+    writing top-level names to src/project.egg-info/top_level.txt
+    reading manifest file 'src/project.egg-info/SOURCES.txt'
+    writing manifest file 'src/project.egg-info/SOURCES.txt'
     installing to build/bdist.linux-x86_64/wheel
     running install
+    running install_lib
+    creating build/bdist.linux-x86_64
+    creating build/bdist.linux-x86_64/wheel
+    copying build/lib/__init__.py -> build/bdist.linux-x86_64/wheel
     running install_egg_info
-    running egg_info
-    writing project.egg-info/PKG-INFO
-    writing dependency_links to project.egg-info/dependency_links.txt
-    writing requirements to project.egg-info/requires.txt
-    writing top-level names to project.egg-info/top_level.txt
-    reading manifest file 'project.egg-info/SOURCES.txt'
-    writing manifest file 'project.egg-info/SOURCES.txt'
-    Copying project.egg-info to build/bdist.linux-x86_64/wheel/project-0.1.0-py3.12.egg-info
+    Copying src/project.egg-info to build/bdist.linux-x86_64/wheel/project-0.1.0-py3.12.egg-info
     running install_scripts
     creating build/bdist.linux-x86_64/wheel/project-0.1.0.dist-info/WHEEL
     creating '[TEMP_DIR]/project/dist/[TMP]/wheel' to it
+    adding '__init__.py'
     adding 'project-0.1.0.dist-info/METADATA'
     adding 'project-0.1.0.dist-info/WHEEL'
     adding 'project-0.1.0.dist-info/top_level.txt'