Fix easy_install not recognizing win32.exe files that include a custom bitmap.

(backport from trunk)

--HG--
branch : setuptools-0.6
extra : convert_revision : svn%3A6015fed2-1504-0410-9fe1-9d1591cc4771/sandbox/branches/setuptools-0.6%4051957

EasyInstall.txt

@@ -1194,6 +1194,10 @@ displayed MD5 info (broken onto two lines for readability)::
 Release Notes/Change History
 ============================
 
+0.6c4
+ * Fixed not recogninzing ``win32.exe`` installers that included a custom
+   bitmap.
+
 0.6c3
  * You once again use "python -m easy_install" with Python 2.4 and above.
 

setuptools/command/easy_install.py

@@ -1249,7 +1249,7 @@ def extract_wininst_cfg(dist_filename):
         if tag not in (0x1234567A, 0x1234567B):
             return None     # not a valid tag
 
-        f.seek(prepended-(12+cfglen+bmlen))
+        f.seek(prepended-(12+cfglen))
         cfg = ConfigParser.RawConfigParser({'version':'','target_version':''})
         try:
             cfg.readfp(StringIO.StringIO(f.read(cfglen).split(chr(0),1)[0]))