Add new ErrorGroup exception

Author: berland

Lib/shutil.py

@@ -67,6 +67,9 @@
 class Error(OSError):
     pass
 
+class ErrorGroup(Error):
+    """Used when gathering multiple exceptions"""
+
 class SameFileError(Error):
     """Raised when source and destination are the same file."""
 
@@ -531,10 +534,10 @@ def _copytree(entries, src, dst, symlinks, ignore, copy_function,
             else:
                 # Can raise SpecialFileError or SameFileError
                 copy_function(srcobj, dstname)
-        except SameFileError as err:
-            errors.append((srcname, dstname, str(err)))
+        except ErrorGroup as err_group:
+            errors.extend(err_group.args[0])
         except Error as err:
-            errors.extend(err.args[0])
+            errors.append((srcname, dstname, str(err)))
         except OSError as why:
             errors.append((srcname, dstname, str(why)))
     try:
@@ -544,7 +547,7 @@ def _copytree(entries, src, dst, symlinks, ignore, copy_function,
         if getattr(why, 'winerror', None) is None:
             errors.append((src, dst, str(why)))
     if errors:
-        raise Error(errors)
+        raise ErrorGroup(errors)
     return dst
 
 def copytree(src, dst, symlinks=False, ignore=None, copy_function=copy2,