[gatsby-transformer-remark] excerpt not working for non-English content

[ipy]

Description

If the post doesn't contain a \w character, e.g. all characters are Chinese, the generated excerpt will contain nothing but '…'.
It's actually a bug of underscore.string: esamattis/underscore.string#418

[Chuloo]

@ipy can you provide more info on the supposed bug, possibly create a reproduction? Look through the issue template for a guide. 👍

[ipy]

Description

When the markdown main body starts with non-English characters(\W, not [a-zA-Z0-9]), the generated excerpt by gatsby-transformer-remark contains nothing but '…'.

Steps to reproduce

Start a new blog:

gatsby new gatsby-blog https://github.com/gatsbyjs/gatsby-starter-blog
gatsby develop

Change the content to 咸鸭蛋很好吃。 and repeat it:

Check the result:

Expected result

Should be:

咸鸭蛋很好吃。 咸鸭蛋很好吃。 咸鸭蛋很好吃。 咸鸭蛋很好吃。 咸鸭蛋很好吃。 咸鸭蛋很好吃。 咸鸭蛋很好吃。 咸鸭蛋很好吃。 咸鸭蛋很好吃。 咸鸭蛋很好吃。 咸鸭蛋很好吃。 咸鸭蛋很好吃。 咸鸭蛋很好吃。 咸鸭蛋很好吃。 咸鸭蛋很好吃。 咸鸭蛋很好吃。 咸鸭蛋很好吃。 咸鸭蛋很…

Actual result

As seen in the image above, only … generated.

Environment

System:
OS: Windows 10
CPU: x64 Intel(R) Core(TM) i5-4690 CPU @ 3.50GHz
Binaries:
Yarn: 1.3.2 - C:\Program Files (x86)\Yarn\bin\yarn.CMD
npm: 5.3.0 - C:\Program Files\nodejs\npm.CMD
Browsers:
Edge: 41.16299.492.0
npmPackages:
gatsby: ^1.9.250 => 1.9.277
gatsby-link: ^1.6.39 => 1.6.46
gatsby-plugin-feed: ^1.3.20 => 1.3.25
gatsby-plugin-google-analytics: ^1.0.29 => 1.0.31
gatsby-plugin-offline: ^1.0.15 => 1.0.18
gatsby-plugin-react-helmet: ^1.0.8 => 1.0.8
gatsby-plugin-sharp: ^1.6.42 => 1.6.48
gatsby-plugin-typography: ^1.7.18 => 1.7.19
gatsby-remark-copy-linked-files: ^1.5.31 => 1.5.37
gatsby-remark-images: ^1.5.61 => 1.5.67
gatsby-remark-prismjs: ^1.2.24 => 1.2.24
gatsby-remark-responsive-iframe: ^1.4.18 => 1.4.20
gatsby-remark-smartypants: ^1.4.12 => 1.4.12
gatsby-source-filesystem: ^1.5.31 => 1.5.39
gatsby-transformer-remark: ^1.7.40 => 1.7.44
gatsby-transformer-sharp: ^1.6.22 => 1.6.27

File contents (if changed)

gatsby-config.js: N/A
package.json: N/A
gatsby-node.js: N/A
gatsby-browser.js: N/A
gatsby-ssr.js: N/A