title: Issue with case-insensitive regex pattern for re.sub()
body: <p>I am doing a dictionary manipulation using regex in Python.I want to remove <code>1dc.com</code> or <code>1DC.com</code> or <code>1dc.COM</code> or <code>1DC.COM</code> from a dictionary item.</p>
  
  <p>Example Dictionary -</p>
  
  <pre><code>{'system_name': 'a1pvdb092', 'fdc_inv_sa_team': 'X2AIX_GBS'}
  {'system_name': 'W00000001.1DC.com', 'fdc_inv_sa_team': 'LAA.BRAZIL.AAA.WINDOWS\n'}
  {'system_name': 'a10000048', 'fdc_inv_sa_team': 'X2AIX_NSS'}
  {'system_name': 'a10000049', 'fdc_inv_sa_team': 'X2AIX_NSS'}
  </code></pre>
  
  <p>Expected Output -</p>
  
  <pre><code>['a1pvdb092']
  ['W00000001']
  ['a10000048']
  ['a10000049']
  </code></pre>
  
  <p>Script -</p>
  
  <pre><code>import re
  from opswareConnect import data
  
  for row in data:
      arg1 = [row["system_name"],]
      arg1 = re.sub('[.1DC.com]\\b', '', str(arg1))
      print arg1
  </code></pre>
  
  <p>Output from the script -</p>
  
  <pre><code>['a1pvdb092']
  ['WBPVAP001Dco']
  ['a10000048']
  ['a10000049']
  </code></pre>