dnn: fix dnn python test files

modules/dnn/test/cityscapes_semsegm_test_enet.py

@@ -4,13 +4,11 @@ import os
 import fnmatch
 import argparse
 
-# sys.path.append('<path to opencv_build_dir/lib>')
-sys.path.append('/home/arrybn/build/opencv_w_contrib/lib')
 try:
     import cv2 as cv
 except ImportError:
-    raise ImportError('Can\'t find opencv. If you\'ve built it from sources without installation, '
-                      'uncomment the line before and insert there path to opencv_build_dir/lib dir')
+    raise ImportError('Can\'t find OpenCV Python module. If you\'ve built it from sources without installation, '
+                      'configure environemnt variable PYTHONPATH to "opencv_build_dir/lib" directory (with "python3" subdirectory if required)')
 try:
     import torch
 except ImportError:

modules/dnn/test/imagenet_cls_test_alexnet.py

@@ -5,20 +5,16 @@ import os
 import argparse
 import time
 
-# sys.path.append('<path to git/caffe/python dir>')
-sys.path.append('/home/arrybn/git/caffe/python')
 try:
     import caffe
 except ImportError:
-    raise ImportError('Can\'t find caffe. If you\'ve built it from sources without installation, '
-                      'uncomment the line before and insert there path to git/caffe/python dir')
-# sys.path.append('<path to opencv_build_dir/lib>')
-sys.path.append('/home/arrybn/build/opencv_w_contrib/lib')
+    raise ImportError('Can\'t find Caffe Python module. If you\'ve built it from sources without installation, '
+                      'configure environemnt variable PYTHONPATH to "git/caffe/python" directory')
 try:
     import cv2 as cv
 except ImportError:
-    raise ImportError('Can\'t find opencv. If you\'ve built it from sources without installation, '
-                      'uncomment the line before and insert there path to opencv_build_dir/lib dir')
+    raise ImportError('Can\'t find OpenCV Python module. If you\'ve built it from sources without installation, '
+                      'configure environemnt variable PYTHONPATH to "opencv_build_dir/lib" directory (with "python3" subdirectory if required)')
 
 
 class DataFetch(object):

modules/dnn/test/imagenet_cls_test_googlenet.py

@@ -3,20 +3,16 @@ import sys
 import os
 import argparse
 from imagenet_cls_test_alexnet import MeanChannelsFetch, CaffeModel, DnnCaffeModel, ClsAccEvaluation
-# sys.path.append('<path to git/caffe/python dir>')
-sys.path.append('/home/arrybn/git/caffe/python')
 try:
     import caffe
 except ImportError:
-    raise ImportError('Can\'t find caffe. If you\'ve built it from sources without installation, '
-                      'uncomment the line before and insert there path to git/caffe/python dir')
-# sys.path.append('<path to opencv_build_dir/lib>')
-sys.path.append('/home/arrybn/build/opencv_w_contrib/lib')
+    raise ImportError('Can\'t find Caffe Python module. If you\'ve built it from sources without installation, '
+                      'configure environemnt variable PYTHONPATH to "git/caffe/python" directory')
 try:
     import cv2 as cv
 except ImportError:
-    raise ImportError('Can\'t find opencv. If you\'ve built it from sources without installation, '
-                      'uncomment the line before and insert there path to opencv_build_dir/lib dir')
+    raise ImportError('Can\'t find OpenCV Python module. If you\'ve built it from sources without installation, '
+                      'configure environemnt variable PYTHONPATH to "opencv_build_dir/lib" directory (with "python3" subdirectory if required)')
 
 if __name__ == "__main__":
     parser = argparse.ArgumentParser()

modules/dnn/test/imagenet_cls_test_inception.py

@@ -5,13 +5,11 @@ import argparse
 import tensorflow as tf
 from tensorflow.python.platform import gfile
 from imagenet_cls_test_alexnet import MeanValueFetch, DnnCaffeModel, Framework, ClsAccEvaluation
-# sys.path.append('<path to opencv_build_dir/lib>')
-sys.path.append('/home/arrybn/build/opencv_w_contrib/lib')
 try:
     import cv2 as cv
 except ImportError:
-    raise ImportError('Can\'t find opencv. If you\'ve built it from sources without installation, '
-                      'uncomment the line before and insert there path to opencv_build_dir/lib dir')
+    raise ImportError('Can\'t find OpenCV Python module. If you\'ve built it from sources without installation, '
+                      'configure environemnt variable PYTHONPATH to "opencv_build_dir/lib" directory (with "python3" subdirectory if required)')
 
 # If you've got an exception "Cannot load libmkl_avx.so or libmkl_def.so" or similar, try to export next variable
 # before runnigng the script:

modules/dnn/test/pascal_semsegm_test_fcn.py

@@ -5,12 +5,11 @@ import argparse
 import time
 
 from imagenet_cls_test_alexnet import CaffeModel, DnnCaffeModel
-sys.path.append('/home/arrybn/build/opencv_w_contrib/lib')
 try:
     import cv2 as cv
 except ImportError:
-    raise ImportError('Can\'t find opencv. If you\'ve built it from sources without installation, '
-                      'uncomment the line before and insert there path to opencv_build_dir/lib dir')
+    raise ImportError('Can\'t find OpenCV Python module. If you\'ve built it from sources without installation, '
+                      'configure environemnt variable PYTHONPATH to "opencv_build_dir/lib" directory (with "python3" subdirectory if required)')
 
 
 def get_metrics(conf_mat):