[Bug Report] el-select will show value not label after deleting an item if don't use reserve-keyword

[bitjjj]

Element UI version

2.11.1

OS/Browsers version

Chrome / 75

Vue version

2.5.2

Reproduction Link

https://codepen.io/bitjjj/pen/qejpyx

Steps to reproduce

1. select some items
2. delete an item

What is Expected?

select should still show item's label not value

What is actually happening?

select show item's value after deleting an item

[raymond-cat]

I also encountered, the original selection data will be cleared