Restore cpoptions before calling finish

The user's 'cpoptions' are saved and restored when this script finishes
normally, however there are some cases where this script finishes early,
and where the user's 'cpoptions' are not restored beforehand.

plugin/youcompleteme.vim

@@ -19,18 +19,26 @@
 let s:save_cpo = &cpo
 set cpo&vim
 
+function! s:restore_cpo()
+  let &cpo = s:save_cpo
+  unlet s:save_cpo
+endfunction
+
 if exists( "g:loaded_youcompleteme" )
+  call s:restore_cpo()
   finish
 elseif v:version < 703 || (v:version == 703 && !has('patch584'))
   echohl WarningMsg |
         \ echomsg "YouCompleteMe unavailable: requires Vim 7.3.584+" |
         \ echohl None
+  call s:restore_cpo()
   finish
 elseif !has( 'python' )
   echohl WarningMsg |
         \ echomsg "YouCompleteMe unavailable: requires Vim compiled with " .
         \ " Python 2.x support" |
         \ echohl None
+  call s:restore_cpo()
   finish
 endif
 
@@ -60,6 +68,7 @@ if g:ycm_check_if_ycm_core_present && !s:HasYcmCore()
         \ "ycm_core.[so|pyd|dll] not detected; you need to compile " .
         \ "YCM before using it. Read the docs!" |
         \ echohl None
+  call s:restore_cpo()
   finish
 endif
 
@@ -152,5 +161,4 @@ augroup youcompletemeStart
 augroup END
 
 " This is basic vim plugin boilerplate
-let &cpo = s:save_cpo
+call s:restore_cpo()
-unlet s:save_cpo