[gatsby-remark-images] Autolinking images overrides other links

[jlengstorf]

Description

When using gatsby-remark-images, if the linkImagesToOriginal is set to true (which is the default), all images will be linked to their original, even if they're already wrapped in a link.

Steps to reproduce

• Demo: https://priceless-wing-6269cd.netlify.com/
• Repo: https://github.com/jlengstorf/gatsby-remark-images-link-override-bug

# clone the repo
git clone https://github.com/jlengstorf/gatsby-remark-images-link-override-bug
cd gatsby-remark-images-link-override-bug/

# install dependencies
npm i

# start the repo
npm run develop

Load `http://localhost:8000/

Expected result

Images with links should preserve those links.

Actual result

Links are overridden with a link to the image. (Actually, they're double-wrapped, but the HTML parser drops the outer link.)

Environment

  System:
    OS: macOS High Sierra 10.13.6
    CPU: x64 Intel(R) Core(TM) i7-7820HQ CPU @ 2.90GHz
    Shell: 3.2.57 - /bin/bash
  Binaries:
    Node: 10.1.0 - ~/.nvm/versions/node/v10.1.0/bin/node
    Yarn: 1.9.2 - /usr/local/bin/yarn
    npm: 5.6.0 - ~/.nvm/versions/node/v10.1.0/bin/npm
  Browsers:
    Chrome: 68.0.3440.84
    Firefox: 60.0.2
    Safari: 11.1.2
  npmPackages:
    gatsby: next => 2.0.0-beta.66 
    gatsby-plugin-react-helmet: next => 3.0.0-beta.4 
    gatsby-plugin-sharp: next => 2.0.0-beta.7 
    gatsby-remark-images: next => 2.0.1-beta.9 
    gatsby-source-filesystem: next => 2.0.1-beta.10 
    gatsby-transformer-remark: next => 2.1.1-beta.5