LilyPond for Windows 2.7.19, Python

[Thomas Scharkowski]

Convert-ly gives the following error message:
--
Traceback (most recent call last):
  File "C:\Programme\LilyPond\usr\bin\convert-ly.py", line 32, in ?
    import lilylib as ly
  File "C:\PROGRA~1\LilyPond\usr\bin\lilylib.py", line 22, in ?
    import tempfile
  File "/home/hanwen/src/mingw/mingw/inst/python-2.4.2-
1/usr/lib/python2.4/tempfile.py", line 33, in ?
  File "/home/hanwen/src/mingw/mingw/inst/python-2.4.2-
1/usr/lib/python2.4/random.py", line 44, in ?
ImportError: No module named math
Process convert-ly.py exited with code 1
--

In version 2.7.12 it worked, the above error also occurs in 2.7.17 
and 2.7.18.

Thomas
Windows XP