build,win: find Python in paths with spaces

When looking for Python in the registry, as specified in PEP514,
this was not able to handle installations in a path with spaces,
like Program Files. This ensures the whole path is used, fixing the
issue.

PR-URL: #29236
Reviewed-By: Christian Clauss <cclauss@me.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

tools/msvs/find_python.cmd

@@ -1,6 +1,8 @@
 @IF NOT DEFINED DEBUG_HELPER @ECHO OFF
+
 echo Looking for Python 2.x
-SETLOCAL
+setlocal enabledelayedexpansion
+
 :: If python.exe is in %Path%, just validate
 FOR /F "delims=" %%a IN ('where python.exe 2^> NUL') DO (
   SET need_path=0
@@ -11,32 +13,36 @@ FOR /F "delims=" %%a IN ('where python.exe 2^> NUL') DO (
 :: Query the 3 locations mentioned in PEP 514 for a python2 InstallPath
 FOR %%K IN ( "HKCU\Software", "HKLM\SOFTWARE", "HKLM\Software\Wow6432Node") DO (
   SET need_path=1
-  CALL :find-main-branch %%K
+  CALL :find-versions-v2 %%K
   :: If validate returns 0 just jump to the end
   IF NOT ERRORLEVEL 1 GOTO :validate
 )
+
 goto :no-python
 
-:: Helper subroutine to handle quotes in %1
-:find-main-branch
-SET main_key="%~1\Python\PythonCore"
-REG QUERY %main_key% /s 2> NUL | findstr "2." | findstr InstallPath > NUL 2> NUL
-IF NOT ERRORLEVEL 1 CALL :find-key %main_key%
-EXIT /B
-
-:: Query registry sub-tree for InstallPath
-:find-key
-FOR /F "delims=" %%a IN ('REG QUERY %1 /s 2^> NUL ^| findstr "2." ^| findstr InstallPath') DO IF NOT ERRORLEVEL 1 CALL :find-path %%a
-EXIT /B
-
-:: Parse the value of %1 as the path for python.exe
-:find-path
-FOR /F "tokens=3*" %%a IN ('REG QUERY %1 /ve') DO (
-  SET pt=%%a
-  IF NOT ERRORLEVEL 1 SET p=%pt%
-  EXIT /B 0
+
+:: Find Python 2 installations in a registry location
+:find-versions-v2
+for /f "delims=" %%a in ('reg query "%~1\Python\PythonCore" /f * /k 2^> nul ^| findstr /r ^^HK ^| findstr "\\2\."') do (
+  call :read-installpath %%a
+  if not errorlevel 1 exit /b 0
 )
-EXIT /B 1
+exit /b 1
+
+:: Read the InstallPath of a given Environment Key to %p%
+:: https://www.python.org/dev/peps/pep-0514/#installpath
+:read-installpath
+:: %%a will receive token 3
+:: %%b will receive *, corresponding to token 4 and all after
+for /f "skip=2 tokens=3*" %%a in ('reg query "%1\InstallPath" /ve /t REG_SZ 2^> nul') do (
+  set "head=%%a"
+  set "tail=%%b"
+  set "p=!head!"
+  if not "!tail!"=="" set "p=!head! !tail!"
+  exit /b 0
+)
+exit /b 1
+
 
 :: Check if %p% holds a path to a real python2 executable
 :validate