Make make.py build docs under python 3

Author: dmcdougall

doc/make.py

@@ -89,13 +89,13 @@ def copytree(src, dst, symlinks=False, ignore=None):
                 copy2(srcname, dstname)
         # catch the Error from the recursive copytree so that we can
         # continue with other files
-        except Error, err:
+        except Error as err:
             errors.extend(err.args[0])
-        except EnvironmentError, why:
+        except EnvironmentError as why:
             errors.append((srcname, dstname, str(why)))
     try:
         copystat(src, dst)
-    except OSError, why:
+    except OSError as why:
         if WindowsError is not None and isinstance(why, WindowsError):
             # Copying file access times may fail on Windows
             pass