Try to prevent the resize of minibuffer window

* ivy.el (ivy--insert-minibuffer): Temporarily bind
  `resize-mini-windows' to nil.

From its doc:
    A value of `grow-only', the default, means let mini-windows grow only;
    they return to their normal size when the minibuffer is closed, or the
    echo area becomes empty.

It could be that an update catches this minibuffer empty during
`ivy--insert-minibuffer'.

Re abo-abo#77

ivy.el

@@ -934,10 +934,11 @@ Should be run via minibuffer `post-command-hook'."
 
 (defun ivy--insert-minibuffer (text)
   "Insert TEXT into minibuffer with appropriate cleanup."
-  (ivy--cleanup)
-  (let ((buffer-undo-list t)
+  (let ((resize-mini-windows nil)
+        (buffer-undo-list t)
         (update-fn (ivy-state-update-fn ivy-last))
         deactivate-mark)
+    (ivy--cleanup)
     (when update-fn
       (funcall update-fn))
     (ivy--insert-prompt)