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

miss-islington · zooba · web-flow · commit 1ff04dcadfb5 · 2019-03-27T17:01:31.000-07:00
(cherry picked from commit b95a79c) Co-authored-by: Steve Dower <steve.dower@microsoft.com>
diff --git 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
