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

diff --git a/PCbuild/get_externals.bat b/PCbuild/get_externals.bat
index cbeb5a19b55b98a42d140a32a6c24202f5cb3f9e..887fdc9411710e71b2e63bda0eaf9f55b34e2841 100644 (file)
--- 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