existing meta tags were removed unexpectedly

[NeverBehave]

• I confirm that this is an issue rather than a question.

Bug report

Steps to reproduce

Follow getting-started and start a minimal instance

What is expected?

The page generated should have all meta tags, like viewport, description.

What is actually happening?

The meta tags in the static html page e.g. viewport was removed after the page loaded

Other relevant information

From view source, the viewport tag appears.

But after the page is loaded, only description meta remained

It is believed that this function update the meta tag

vuepress/packages/@vuepress/core/lib/client/root-mixins/updateMeta.js

Line 62 in 01cd096

function updateMetaTags (newMetaTags, currentMetaTags) {

• Output of npx vuepress info in my VuePress project:

Environment Info:

  System:
    OS: Linux 5.4 Manjaro Linux
    CPU: (8) x64 AMD Ryzen 5 PRO 3400GE w/ Radeon Vega Graphics
  Binaries:
    Node: 13.13.0 - /usr/bin/node
    Yarn: 1.22.4 - /usr/bin/yarn
    npm: 6.14.4 - /usr/bin/npm
  Browsers:
    Chrome: Not Found
    Firefox: 75.0
  npmPackages:
    @vuepress/core: Not Found
    @vuepress/theme-default: Not Found
    vuepress: Not Found
  npmGlobalPackages:
    vuepress: Not Found

[NeverBehave]

#2164

It looks like it is still replacing...

[NeverBehave]

Close #2332