Increase verbosity of Windows installer initalize message.

New submission from verm <None>:

The Windows installer can be very unhelpful in it's error message in [source:trunk/win32/pyx.x-foo.iss.template@23264#L53 trunk/win32/pyx.x-foo.iss.template -> InitalizeSetup]

{{{
"Python does not appear to be installed"
"Please install Python before attempting to install Twisted."
}}}

The actual Error was Python2.5 amd64 was installed when the 32bit version is required.  It would be nice to have a few extra checks here for such cases as situations like these when there is no way to debug the actual error can result in many hours of wasted time.

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Type     : enhancement
Component: core
Keywords : installer
Priority : normal
Nosy     : 
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http://twistedmatrix.com/trac/ticket/3794