[GHC] #7333: python2

[GHC]

#7333: python2
------------------------------+---------------------------------------------
 Reporter:  michalt           |          Owner:                  
     Type:  bug               |         Status:  new             
 Priority:  normal            |      Component:  Build System    
  Version:  7.6.1             |       Keywords:                  
       Os:  Unknown/Multiple  |   Architecture:  Unknown/Multiple
  Failure:  None/Unknown      |       Testcase:                  
Blockedby:                    |       Blocking:                  
  Related:                    |  
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 Currently GHC assumes that the ```python``` command defaults to Python
 2.x, but on
 some systems (e.g., Arch Linux) it's already Python 3.x.  This breaks the
 testsuite completely.  According to
 http://www.python.org/dev/peps/pep-0394/ on
 *nix systems one should prefer ```python2``` command.  I'm not very
 familiar with the
 build system of GHC but my quick solution is to:

  - make configure.ac check for python2
  - make the testsuite also try python2 first
  - remove the shebang line from ```calibrate``` (testsuite/timeout) since
 make already calls it with the value
    of ```PYTHON``` variable
  - change the shebang in ```timeout.py``` (in testsuite/timeout) to use
 python2, which
    should be safe on Unix like systems (and on Windows we don't actually
 use timeout.py)

 Btw is the ```PythonCmd``` (defined by configure.ac) actually used
 somewhere -- I can't
 seem to find where...

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7333>
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