PY-17241 Don't include packages in excluded project venv directory in setup.py

It happened because interpreter paths inside excluded virtualenv directory
are not considered excluded themselves. Now we stop going deeper into the
project structure once we've found a directory that is not a valid traditional
style package (unless it's a root).

python/src/com/jetbrains/python/packaging/PyPackageUtil.java

@@ -312,10 +312,14 @@ public class PyPackageUtil {
     VfsUtilCore.visitChildrenRecursively(root, new VirtualFileVisitor() {
       @Override
       public boolean visitFile(@NotNull VirtualFile file) {
+        if (file.equals(root)) {
+          return true;
+        }
         if (!fileIndex.isExcluded(file) && file.isDirectory() && file.findChild(PyNames.INIT_DOT_PY) != null) {
           results.add(VfsUtilCore.getRelativePath(file, root, '.'));
+          return true;
         }
-        return true;
+        return false;
       }
     });
   }

python/testSrc/com/jetbrains/python/packaging/PyPackageUtilTest.java

@@ -18,6 +18,7 @@ package com.jetbrains.python.packaging;
 import com.google.common.collect.ImmutableMap;
 import com.intellij.openapi.command.WriteCommandAction;
 import com.intellij.openapi.module.Module;
+import com.intellij.openapi.vfs.VirtualFile;
 import com.jetbrains.python.fixtures.PyTestCase;
 import com.jetbrains.python.psi.LanguageLevel;
 import com.jetbrains.python.psi.PyCallExpression;
@@ -264,4 +265,20 @@ public class PyPackageUtilTest extends PyTestCase {
       assertEquals(text, argument.getText());
     }
   }
+
+  // PY-17241
+  public void testCollectingPackageNamesIgnoresExcludedDirectoriesWithSdkRoots() {
+    addExcludedRoot("env");
+    final VirtualFile sdkRoot = myFixture.findFileInTempDir("env/site-packages");
+    runWithAdditionalClassEntryInSdkRoots(sdkRoot, () -> {
+      final List<String> collected = PyPackageUtil.getPackageNames(myFixture.getModule());
+      assertSameElements(collected, "project", "project.pkg");
+    });
+  }
+
+  // PY-17241
+  public void testCollectingPackageNamesIgnoresChildrenOfDirectoriesWithoutInitPy() {
+    final List<String> collected = PyPackageUtil.getPackageNames(myFixture.getModule());
+    assertSameElements(collected, "project", "project.pkg");
+  }
 }