Allow updating specific plugins.

autoload/vundle/installer.vim

@@ -6,9 +6,21 @@
 " ...    -- any number of bundle specifications (separate arguments)
 " ---------------------------------------------------------------------------
 func! vundle#installer#new(bang, ...) abort
-  let bundles = (a:1 == '') ?
-        \ g:bundles :
-        \ map(copy(a:000), 'vundle#config#bundle(v:val, {})')
+  " No specific plugins are specified. Operate on all plugins.
+  if a:0 == 0
+    let bundles = g:bundles
+  " Specific plugins are specified for update. Update them.
+  elseif (a:bang)
+    let bundles = filter(copy(g:bundles), 'index(a:000, v:val.name) > -1')
+  " Specific plugins are specified for installation. Install them.
+  else
+    let bundles = map(copy(a:000), 'vundle#config#bundle(v:val, {})')
+  endif
+
+  if empty(bundles)
+    echoerr 'No bundles were selected for operation'
+    return
+  endif
 
   let names = vundle#scripts#bundle_names(map(copy(bundles), 'v:val.name_spec'))
   call vundle#scripts#view('Installer',['" Installing plugins to '.expand(g:bundle_dir, 1)], names +  ['Helptags'])

autoload/vundle/scripts.vim

@@ -39,7 +39,12 @@ endf
 "            candidates, see also :h command-completion-custom
 " ---------------------------------------------------------------------------
 func! vundle#scripts#complete(a,c,d)
-  return join(s:load_scripts(0),"\n")
+  " Return only installed plugins if updating
+  if match(a:c, '\v^Plugin%(Install!|Update)') == 0
+    return join(map(copy(g:bundles), 'v:val.name'), "\n")
+  else
+    return join(s:load_scripts(0),"\n")
+  endif
 endf