Try to force python version

- The change in find_package favours the latest Python
- Force cmake to use the one specified
- Put back the echo again since it is needed
diff --git a/build/appveyor/MSVC-appveyor-full.bat b/build/appveyor/MSVC-appveyor-full.bat
index dcdf843..2e81fd5 100644
--- a/build/appveyor/MSVC-appveyor-full.bat
+++ b/build/appveyor/MSVC-appveyor-full.bat
@@ -55,6 +55,8 @@
   EXIT /B 1
 )
 
+:: Put back the @ECHO since vcvars*.bat above disables it
+@ECHO ON
 
 :: compiler and generator detection
 IF /i "%PLATFORM%" == "x64" SET GENARCH= Win64
@@ -88,10 +90,13 @@
 
 IF "%PYTHON_VERSION%" == "" (
   SET WITH_PYTHON=OFF
+  SET CMAKE_PYTHON_OPTS=""
 ) ELSE (
   SET WITH_PYTHON=ON
   IF /i "%PLATFORM%" == "x64" (SET PTEXT=-x64)
-  SET PATH=C:\Python%PYTHON_VERSION:.=%!PTEXT!\scripts;C:\Python%PYTHON_VERSION:.=%!PTEXT!;!PATH!
+  SET PYTHON_ROOT=C:\Python%PYTHON_VERSION:.=%!PTEXT!
+  SET PATH=!PYTHON_ROOT!\scripts;!PYTHON_ROOT!;!PATH!
+  SET CMAKE_PYTHON_OPTS=-DPython3_FIND_STRATEGY=LOCATION -DPython3_ROOT=!PYTHON_ROOT!
 )
 
 IF "%CONFIGURATION%" == "Debug" (SET ZLIB_LIB_SUFFIX=d)
@@ -101,9 +106,10 @@
   SET PATH=C:\Qt\%QT_VERSION%\%PROFILE%!QTEXT!\bin;!PATH!
 )
 
-
+@ECHO OFF
 CALL win_showenv.bat || EXIT /B
 MKDIR "%WIN3P%" || EXIT /B
+@ECHO ON
 
 choco feature enable -n allowGlobalConfirmation || EXIT /B
 
@@ -178,7 +184,7 @@
   -DOPENSSL_USE_STATIC_LIBS=OFF ^
   -DZLIB_LIBRARY="%WIN3P%\zlib-inst\lib\zlib%ZLIB_LIB_SUFFIX%.lib" ^
   -DZLIB_ROOT="%WIN3P%\zlib-inst" ^
-  -DWITH_PYTHON=%WITH_PYTHON% || EXIT /B
+  -DWITH_PYTHON=%WITH_PYTHON% %CMAKE_PYTHON_OPTS% || EXIT /B
 
 cmake.exe --build . --config "%CONFIGURATION%" || EXIT /B