[Python-checkins] bpo-36245: Fix more empty environment variable checks (GH-12592)

[Steve Dower]

https://github.com/python/cpython/commit/b95a79c928fc4a6135d91c0c553cb2a63cf15140
commit: b95a79c928fc4a6135d91c0c553cb2a63cf15140
branch: master
author: Steve Dower <steve.dower at microsoft.com>
committer: GitHub <noreply at github.com>
date: 2019-03-27T16:28:41-07:00
summary:

bpo-36245: Fix more empty environment variable checks (GH-12592)

files:
M PCbuild/get_externals.bat

diff --git a/PCbuild/get_externals.bat b/PCbuild/get_externals.bat
index cbeb5a19b55b..887fdc941171 100644
--- a/PCbuild/get_externals.bat
+++ b/PCbuild/get_externals.bat
@@ -2,8 +2,8 @@
 setlocal
 rem Simple script to fetch source for external libraries
 
-if "%PCBUILD%"=="" (set PCBUILD=%~dp0)
-if "%EXTERNALS_DIR%"=="" (set EXTERNALS_DIR=%PCBUILD%\..\externals)
+if NOT DEFINED PCBUILD (set PCBUILD=%~dp0)
+if NOT DEFINED EXTERNALS_DIR (set EXTERNALS_DIR=%PCBUILD%\..\externals)
 
 set DO_FETCH=true
 set DO_CLEAN=false