title: re.sub not replacing all occurrences
body: <p>I'm not a Python developer, but I'm using a Python script to <a href="https://stackoverflow.com/questions/18671/quick-easy-way-to-migrate-sqlite3-to-mysql">convert SQLite to MySQL</a></p>
  
  <p>The suggested script gets close, but no cigar, as they say.</p>
  
  <p>The line giving me a problem is:</p>
  
  <pre><code>line = re.sub(r"([^'])'t'(.)", r"\1THIS_IS_TRUE\2", line)
  </code></pre>
  
  <p>...along with the equivalent line for false ('f'), of course.</p>
  
  <p>The problem I'm seeing is that only the first occurrence of 't' in any given line is replaced.</p>
  
  <p>So, input to the script,</p>
  
  <pre><code>INSERT INTO "cars" VALUES(56,'Bugatti Veyron','BUG 1',32,'t','t','2011-12-14 18:39:16.556916','2011-12-15 11:25:03.675058','81');
  </code></pre>
  
  <p>...gives...</p>
  
  <pre><code>INSERT INTO "cars" VALUES(56,'Bugatti Veyron','BUG 1',32,THIS_IS_TRUE,'t','2011-12-14 18:39:16.556916','2011-12-15 11:25:03.675058','81');
  </code></pre>
  
  <p>I mentioned I'm not a Python developer, but I have tried to fix this myself.  According to the documentation, I understand that re.sub should replace all occurrences of 't'.</p>
  
  <p>I'd appreciate a hint as to why I'm only seeing the first occurrence replaced, thanks.</p>