cannot build on windows

[GNQG]

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

Bug report

Steps to reproduce

• I prepared a reproduction repo, here is the reproduction repo:

• This issue doesn't need a reproduction repro, here is the steps to reproduce

What is expected?

The command yarn build succeeds.

What is actually happening?

The script build:components fails with code 1.

>yarn build
yarn run v1.19.1
$ concurrently "rimraf lib" "npm:build:client" "npm:build:node" "npm:build:components"
[0] rimraf lib exited with code 0
[build:client]
[build:client] > @vuepress/plugin-blog@1.5.1 build:client .\vuepress-plugin-blog
[build:client] > tsc -p tsconfig.client.json
[build:client]
[build:components]
[build:components] > @vuepress/plugin-blog@1.5.1 build:components .\vuepress-plugin-blog
[build:components] > mkdir -p lib/client/components && cp -r src/client/components lib/client
[build:components]
[build:node]
[build:node] > @vuepress/plugin-blog@1.5.1 build:node .\vuepress-plugin-blog
[build:node] > tsc -p tsconfig.node.json
[build:node]
[build:components] The syntax of the command is incorrect.
[build:components] npm ERR! code ELIFECYCLE
[build:components] npm ERR! errno 1
[build:components] npm ERR! @vuepress/plugin-blog@1.5.1 build:components: `mkdir -p lib/client/components && cp -r src/client/components lib/client`
[build:components] npm ERR! Exit status 1
[build:components] npm ERR!
[build:components] npm ERR! Failed at the @vuepress/plugin-blog@1.5.1 build:components script.
[build:components] npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
[build:components]
[build:components] npm ERR! A complete log of this run can be found in:
[build:components] npm ERR!     cache\_logs\2019-11-27T02_53_41_037Z-debug.log
[build:components] npm run build:components exited with code 1
[build:client] npm run build:client exited with code 0
[build:node] npm run build:node exited with code 0
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

Other relevant information

The cause of this issue is that mkdir on windows' cmd.exe does not support -p option and path separator / (allows only \).

• npx vuepress info: