win32: favor local mercurial.ini over registry key

Hopefully this is the best of both worlds. Multiple py2exe based
installers can coexist on one machine, while source and lib based
Mercurial users can still use a registry key in lieu of resorting to
HGRCPATH.

mercurial/util_win32.py

@@ -180,6 +180,17 b' def testpid(pid):'
 
 def system_rcpath_win32():
     '''return default os-specific hgrc search path'''
+    proc = win32api.GetCurrentProcess()
+    try:
+        # This will fail on windows < NT
+        filename = win32process.GetModuleFileNameEx(proc, 0)
+    except:
+        filename = win32api.GetModuleFileName(0)
+    # Use mercurial.ini found in directory with hg.exe
+    progrc = os.path.join(os.path.dirname(filename), 'mercurial.ini')
+    if os.path.isfile(progrc):
+        return [progrc]
+    # else look for a system rcpath in the registry
     try:
         value = win32api.RegQueryValue(
                 win32con.HKEY_LOCAL_MACHINE, 'SOFTWARE\\Mercurial')
@@ -193,14 +204,7 b' def system_rcpath_win32():'
                         rcpath.append(os.path.join(p, f))
         return rcpath
     except pywintypes.error:
-        pass
-    proc = win32api.GetCurrentProcess()
-    try:
-        # This will fail on windows < NT
-        filename = win32process.GetModuleFileNameEx(proc, 0)
-    except:
-        filename = win32api.GetModuleFileName(0)
-    return [os.path.join(os.path.dirname(filename), 'mercurial.ini')]
+        return []
 
 def user_rcpath_win32():
     '''return os-specific hgrc search path to the user dir'''