Index: Setup/build.bat
==================================================================
--- Setup/build.bat
+++ Setup/build.bat
@@ -581,16 +581,20 @@
   )
   ENDLOCAL && SET %2=%VALUE%
   GOTO :EOF
 
 :fn_UnsetVariable
+  SETLOCAL
   SET VALUE=%1
   IF DEFINED VALUE (
-    SET %VALUE%=
     SET VALUE=
-    CALL :fn_ResetErrorLevel
+    ENDLOCAL
+    SET %VALUE%=
+  ) ELSE (
+    ENDLOCAL
   )
+  CALL :fn_ResetErrorLevel
   GOTO :EOF
 
 :fn_ResetErrorLevel
   VERIFY > NUL
   GOTO :EOF

Index: Setup/build_ce_200x.bat
==================================================================
--- Setup/build_ce_200x.bat
+++ Setup/build_ce_200x.bat
@@ -96,16 +96,20 @@
   SET __ECHO_CMD=
   CALL :fn_ResetErrorLevel
   GOTO :EOF
 
 :fn_UnsetVariable
+  SETLOCAL
   SET VALUE=%1
   IF DEFINED VALUE (
-    SET %VALUE%=
     SET VALUE=
-    CALL :fn_ResetErrorLevel
+    ENDLOCAL
+    SET %VALUE%=
+  ) ELSE (
+    ENDLOCAL
   )
+  CALL :fn_ResetErrorLevel
   GOTO :EOF
 
 :fn_ResetErrorLevel
   VERIFY > NUL
   GOTO :EOF

Index: Setup/release_all.bat
==================================================================
--- Setup/release_all.bat
+++ Setup/release_all.bat
@@ -99,16 +99,20 @@
   )
   ENDLOCAL && SET %2=%VALUE%
   GOTO :EOF
 
 :fn_UnsetVariable
+  SETLOCAL
   SET VALUE=%1
   IF DEFINED VALUE (
-    SET %VALUE%=
     SET VALUE=
-    CALL :fn_ResetErrorLevel
+    ENDLOCAL
+    SET %VALUE%=
+  ) ELSE (
+    ENDLOCAL
   )
+  CALL :fn_ResetErrorLevel
   GOTO :EOF
 
 :fn_SetExtraPlatform
   IF "%~1" == "" GOTO :EOF
   SETLOCAL

Index: Setup/test_all.bat
==================================================================
--- Setup/test_all.bat
+++ Setup/test_all.bat
@@ -289,16 +289,20 @@
     SET HAVE_EF6=1
   )
   GOTO :EOF
 
 :fn_UnsetVariable
+  SETLOCAL
   SET VALUE=%1
   IF DEFINED VALUE (
-    SET %VALUE%=
     SET VALUE=
-    CALL :fn_ResetErrorLevel
+    ENDLOCAL
+    SET %VALUE%=
+  ) ELSE (
+    ENDLOCAL
   )
+  CALL :fn_ResetErrorLevel
   GOTO :EOF
 
 :fn_ResetErrorLevel
   VERIFY > NUL
   GOTO :EOF

Index: Setup/test_ce_200x.bat
==================================================================
--- Setup/test_ce_200x.bat
+++ Setup/test_ce_200x.bat
@@ -124,16 +124,20 @@
   SET __ECHO_CMD=
   CALL :fn_ResetErrorLevel
   GOTO :EOF
 
 :fn_UnsetVariable
+  SETLOCAL
   SET VALUE=%1
   IF DEFINED VALUE (
-    SET %VALUE%=
     SET VALUE=
-    CALL :fn_ResetErrorLevel
+    ENDLOCAL
+    SET %VALUE%=
+  ) ELSE (
+    ENDLOCAL
   )
+  CALL :fn_ResetErrorLevel
   GOTO :EOF
 
 :fn_ResetErrorLevel
   VERIFY > NUL
   GOTO :EOF