Merge branch 'PHP-7.1' into PHP-7.2

* PHP-7.1:
  Yet one attempt to mitigate the unzip error on AppVeyor

Author: weltling

appveyor/build.bat

@@ -2,6 +2,7 @@
 
 set SDK_REMOTE=https://github.com/OSTC/php-sdk-binary-tools.git
 set SDK_BRANCH=%PHP_BUILD_SDK_BRANCH%
+set SDK_RUNNER=%PHP_BUILD_CACHE_SDK_DIR%\phpsdk-%PHP_BUILD_CRT%-%PLATFORM%.bat
 
 if not exist "%PHP_BUILD_CACHE_BASE_DIR%" (
 	echo Creating %PHP_BUILD_CACHE_BASE_DIR%
@@ -13,6 +14,10 @@ if not exist "%PHP_BUILD_OBJ_DIR%" (
 	mkdir "%PHP_BUILD_OBJ_DIR%"
 )
 
+if not exist "%SDK_RUNNER%" (
+	if exist "%PHP_BUILD_CACHE_SDK_DIR%" rmdir /s /q "%PHP_BUILD_CACHE_SDK_DIR%"
+)
+
 if not exist "%PHP_BUILD_CACHE_SDK_DIR%" (
 	echo Cloning remote SDK repository
 	git clone --branch %SDK_BRANCH% %SDK_REMOTE% "%PHP_BUILD_CACHE_SDK_DIR%" 2>&1 
@@ -21,14 +26,13 @@ if not exist "%PHP_BUILD_CACHE_SDK_DIR%" (
 for /f "tokens=*" %%a in ('type %PHP_BUILD_CACHE_SDK_DIR%\VERSION') do set GOT_SDK_VER=%%a
 echo Got SDK version %GOT_SDK_VER%
 if NOT "%GOT_SDK_VER%" == "%PHP_BUILD_SDK_BRANCH:~8%" (
-	echo Updating to the configured SDK version %SDK_BRANCH:~8%
+	echo Switching to the configured SDK version %SDK_BRANCH:~8%
 	echo Fetching remote SDK repository
 	git --git-dir="%PHP_BUILD_CACHE_SDK_DIR%\.git" --work-tree="%PHP_BUILD_CACHE_SDK_DIR%" fetch --prune origin 2>&1
 	echo Checkout SDK repository branch
 	git --git-dir="%PHP_BUILD_CACHE_SDK_DIR%\.git" --work-tree="%PHP_BUILD_CACHE_SDK_DIR%" checkout --force %SDK_BRANCH% 
 )
 
-set SDK_RUNNER=%PHP_BUILD_CACHE_SDK_DIR%\phpsdk-%PHP_BUILD_CRT%-%PLATFORM%.bat
 if not exist "%SDK_RUNNER%" (
 	echo "%SDK_RUNNER%" doesn't exist
 	exit /b 3