# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1342476090 -7200
# Node ID 4e984fd40300484ed4e4e4f25021475a86a8ad5a
# Parent  ead1f4d7710ef416d9438f6a52001f4ec49f9aff
Prevent getHeader from raising an exception when a header is absent, returning None instead.

diff -r ead1f4d7710e -r 4e984fd40300 MoinSupport.py
--- a/MoinSupport.py	Sun Jul 15 19:55:33 2012 +0200
+++ b/MoinSupport.py	Tue Jul 17 00:01:30 2012 +0200
@@ -225,12 +225,21 @@
         return request.path
 
 def getHeader(request, header_name, prefix=None):
+
+    """
+    Using the 'request', return the value of the header with the given
+    'header_name', using the optional 'prefix' to obtain protocol-specific
+    headers if necessary.
+
+    If no value is found for the given 'header_name', None is returned.
+    """
+
     if hasattr(request, "getHeader"):
         return request.getHeader(header_name)
     elif hasattr(request, "headers"):
-        return request.headers[header_name]
+        return request.headers.get(header_name)
     else:
-        return request.env[(prefix and prefix + "_" or "") + header_name.upper()]
+        return request.env.get((prefix and prefix + "_" or "") + header_name.upper())
 
 # Content/media type and preferences support.