title: Psycopg2 install with pip works but cannot import module on OS X 10.9
body: <p>I've installed psycopg2 with </p>
  
  <pre><code>pip install psycopg2
  </code></pre>
  
  <p>and it worked just fine. The install output had a couple of warning along the lines of </p>
  
  <pre><code>In file included from ./psycopg/psycopg.h:33:
  ./psycopg/config.h:71:13: warning: unused function 'Dprintf' [-Wunused-function]
  static void Dprintf(const char *fmt, ...) {}
              ^
  1 warning generated.
  </code></pre>
  
  <p>but in the end it says</p>
  
  <pre><code>Successfully installed psycopg2
  </code></pre>
  
  <p>and it also appears when I run <code>pip list</code>.</p>
  
  <p>Now when I try to import it in python I get an error:</p>
  
  <pre><code>$ python
  Python 2.7.5 (default, Aug 25 2013, 00:04:04)
  [GCC 4.2.1 Compatible Apple LLVM 5.0 (clang-500.0.68)] on darwin
  Type "help", "copyright", "credits" or "license" for more information.
  &gt;&gt;&gt; import psycopg2
  Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
  ImportError: No module named psycopg2
  </code></pre>
  
  <p>Why can't Python import the module if it was successfully installed?</p>
  
  <p>(Python 2.7.5 was installed with Homebrew. psycopg2 was installed with pip.)</p>