Merge remote-tracking branch 'upstream/3.4' into merge-3.4

modules/python/bindings/CMakeLists.txt

@@ -11,7 +11,7 @@ set(PYTHON_SOURCE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/../")
 # get list of modules to wrap
 set(OPENCV_PYTHON_MODULES)
 foreach(m ${OPENCV_MODULES_BUILD})
-  if (";${OPENCV_MODULE_${m}_WRAPPERS};" MATCHES ";${MODULE_NAME};" AND HAVE_${m})
+  if (";${OPENCV_MODULE_${m}_WRAPPERS};" MATCHES ";python;" AND HAVE_${m})
     list(APPEND OPENCV_PYTHON_MODULES ${m})
     #message(STATUS "\t${m}")
   endif()

modules/python/package/cv2/__init__.py

@@ -18,6 +18,10 @@ except ImportError:
 
 def bootstrap():
     import sys
+
+    import copy
+    save_sys_path = copy.copy(sys.path)
+
     if hasattr(sys, 'OpenCV_LOADER'):
         print(sys.path)
         raise ImportError('ERROR: recursion is detected during loading of "cv2" binary extensions. Check OpenCV installation.')
@@ -85,6 +89,8 @@ def bootstrap():
     del sys.modules['cv2']
     import cv2
 
+    sys.path = save_sys_path  # multiprocessing should start from bootstrap code (https://github.com/opencv/opencv/issues/18502)
+
     try:
         import sys
         del sys.OpenCV_LOADER