Verify plugin name before git operation on interactive install

If then plugin name check fails during the servicing of a interactive
install request, the operation should leave no traces.

Before this change, git cloning or resetting of the origin remote
occurred before checking the name. This change reverses that.

autoload/vundle/installer.vim

@@ -150,11 +150,11 @@ endf
 " return -- the return value from vundle#installer#install()
 " ---------------------------------------------------------------------------
 func! vundle#installer#install_and_require(bang, name) abort
-  let result = vundle#installer#install(a:bang, a:name)
   let bundle = vundle#config#bundle(a:name, {})
   if empty(bundle)
     return 'error'
   endif
+  let result = vundle#installer#install(a:bang, a:name)
   call vundle#installer#helptags([bundle])
   call vundle#config#require([bundle])
   return result