Make "vs_toolchain.py update" work on case-sensitive file systems

win_toolchain/get_toolchain_if_necessary.py

Index: win_toolchain/get_toolchain_if_necessary.py
diff --git a/win_toolchain/get_toolchain_if_necessary.py b/win_toolchain/get_toolchain_if_necessary.py
index 5ef3246f8a2db32d6c4217f99bfea472c5d0a1e6..12970d6c80e9c693c71743260021a96f91576733 100755
--- a/win_toolchain/get_toolchain_if_necessary.py
+++ b/win_toolchain/get_toolchain_if_necessary.py
@@ -80,12 +80,13 @@ def GetFileList(root):
                          'win_sdk\\debuggers\\x86\\sym\\',
                          'win_sdk\\debuggers\\x64\\sym\\']
   for base, _, files in os.walk(root):
-    paths = [os.path.join(base, f).lower() for f in files]
+    paths = [os.path.join(base, f) for f in files]
     for p in paths:
-      if any(ignored_dir in p for ignored_dir in ignored_directories):
+      p_lower = p.replace('/', '\\').lower()
+      if any(ignored_dir in p_lower for ignored_dir in ignored_directories):
         continue
       file_list.append(p)
-  return sorted(file_list, key=lambda s: s.replace('/', '\\'))
+  return sorted(file_list, key=lambda s: s.replace('/', '\\').lower())
 
 
 def MakeTimestampsFileName(root, sha1):
@@ -158,7 +159,7 @@ def CalculateHash(root, expected_hash):
     if expected_hash:
       path_without_hash = path_without_hash.replace(
           os.path.join(root, expected_hash).replace('/', '\\'), root)
-    digest.update(path_without_hash)
+    digest.update(path_without_hash.lower())
     with open(path, 'rb') as f:
       digest.update(f.read())
   return digest.hexdigest()