title: scons on win32: debugging SConstruct with pdb
body: <p>I'm trying to debug a SConstruct file that's failing deep deep into some obscure function, and I want to step through the code. This is what I tried to do, and failed:</p>
  
  <pre><code>$ python -m pdb `which scons.py`
  &gt; c:\python27\scripts\scons.py(26)&lt;module&gt;()
  -&gt; __revision__ = "src/script/scons.py 5357 2011/09/09 21:31:03 bdeegan"
  (Pdb) b SConstruct:10
  ***  'SConstruct' not found from sys.path
  (Pdb) import sys, os
  (Pdb) sys.path.append(os.getcwd())
  (Pdb) b SConstruct:10
  ***  'SConstruct' not found from sys.path
  (Pdb)
  </code></pre>
  
  <p>If I rename SConstruct to SConstruct.py, it succeeds to set a breakpoint, but of course it doesn't work, because "scons" loads SConstruct, not SConstruct.py.
  Any way to force python to put a breakpoint there?</p>
  
  <p>I'm running this from a msys bash console on a Win7 system.
  Python version:</p>
  
  <pre><code>$ python
  Python 2.7.2 (default, Jun 12 2011, 15:08:59) [MSC v.1500 32 bit (Intel)] on win32
  Type "help", "copyright", "credits" or "license" for more information.
  </code></pre>