On Windows 7, using python 3.4.2 32 bits MSVCv.1600 or 3.4.1 64 bits, all the os.exec*e variants crash:

os.execle('C:/Python34/python.exe','Python.exe','-V',{})

os.execve('C:/Python34/python.exe',['python.exe','-V'],{})

os.execlpe('C:/Python34/python.exe','python.exe','-V',{})

os.execvpe('C:/Python34/python.exe',['python.exe','-V'],{})

Without any error message, windows will just open a "Python.exe has stopped working" window, be the scripts run from an interactive shell or invoking python script.py

On the other hand, 
os.execl('C:/Python34/python.exe','Python.exe','-V')

os.execve('C:/Python34/python.exe',['python.exe','-V'])

os.execlpe('C:/Python34/python.exe','python.exe','-V')

os.execvpe('C:/Python34/python.exe',['python.exe','-V'])

will work perfectly.