As an extra data point, note the behaviour on Windows:

C:\Users\Vinay> \python34\python -m venv "\Temp\aaa bbb"                                                       
                                                                                                               
C:\Users\Vinay> "\Temp\aaa bbb\Scripts\pip" --version                                                          
pip 6.0.8 from C:\Temp\aaa bbb\lib\site-packages (python 3.4)                                                  
                                                                                                               
C:\Users\Vinay> pyzzer -i "\Temp\aaa bbb\Scripts\pip.exe"                                                      
There is a launcher.                                                                                           
Shebang: #!"C:\Temp\aaa bbb\Scripts\python.exe"                                                                
                                                                                                               
                                                                                                               
Archive contents:                                                                                              
  __main__.py                                                                                                  
                                                                                                               
C:\Users\Vinay> "\Temp\aaa bbb\Scripts\python" -m pip install -U pip                                           
You are using pip version 6.0.8, however version 9.0.1 is available.                                           
You should consider upgrading via the 'pip install --upgrade pip' command.                                     
Collecting pip from https://pypi.python.org/packages/b6/ac/7015eb97dc749283ffdec1c3a88ddb8ae03b8fad0f0e611408f1
96358da3/pip-9.0.1-py2.py3-none-any.whl#md5=297dbd16ef53bcef0447d245815f5144                                   
  Using cached pip-9.0.1-py2.py3-none-any.whl                                                                  
Installing collected packages: pip                                                                             
  Found existing installation: pip 6.0.8                                                                       
    Uninstalling pip-6.0.8:                                                                                    
      Successfully uninstalled pip-6.0.8                                                                       
                                                                                                               
Successfully installed pip-9.0.1                                                                               
                                                                                                               
C:\Users\Vinay> "\Temp\aaa bbb\Scripts\pip" --version                                                          
pip 9.0.1 from C:\Temp\aaa bbb\lib\site-packages (python 3.4)