Expand the file name match so that the match end can be used to limit path character substitution.

tools/emacs/trybot-windows.txt

 This file contains sample trybot output from a Windows trybot run.
 It contains a warning and an error but has otherwise been shortened
 for length.
 
 "C:\Program Files (x86)\Xoreax\IncrediBuild\BuildConsole.exe" e:\b\build\slave\win\build\src\build\all.sln "/Cfg=Debug|Win32"
 
 -----------------------------------------------------------------
 IncrediBuild Console 3.60 Internal (build 1156)
 Copyright (C) 2001-2010 Xoreax Software Ltd. All rights reserved.
 -----------------------------------------------------------------
 --------------------Configuration: toolband_proxy_lib - Debug|Win32------------
 Compiling...
 toolband_p.c
 toolband_proxy.cc
 toolband_dlldata.c
 Creating library...
 
 toolband_proxy_lib - 0 error(s), 0 warning(s)
 --------------------Configuration: webcore_bindings - Debug|Win32--------------
 Compiling...
 CSSGrammar.cpp
-e:\b\build\slave\win\build\src\third_party\webkit\javascriptcore\wtf\text\StringImpl.h(90) : warning C4355: 'this' : used in base member initializer list
+e:\b\build\slave\win\build\src\third_party\webkit\javascriptcore\wtf\text\StringImpl.h(90) : warning C4355: 'this' : used in base member initializer list with a gratuitous backslash \ for testing
 e:\b\build\slave\win\build\src\third_party\webkit\webcore\dom\ViewportArguments.h(78) : warning C4305: 'initializing' : truncation from '' to 'bool'
 e:\b\build\slave\win\build\src\build\Debug\obj\global_intermediate\webkit\CSSGrammar.cpp(1930) : warning C4065: switch statement contains 'default' but no 'case' labels
 V8DerivedSources1.cpp
 --------------------Configuration: run_testserver - Debug|Win32----------------
 Compiling...
 run_testserver.cc
 Linking...
 Embedding manifest...
 Embedding manifest... (rc.exe)
 Microsoft (R) Windows (R) Resource Compiler Version 6.1.6723.1
@@ skipping 15 matching lines @@
 ntp_background_util.cc
 
 browser - 6 error(s), 0 warning(s)
  
 1 build system warning(s):
    - PDB instance limit is enabled
  
 ---------------------- Done ----------------------
  
     Build: 244 succeeded, 1 failed, 233 up-to-date, 42 skipped