When client js uses images in render methods, e.g. <img src='...' /> or in css, e.g. background-image: url(...)
these assets fail to load. This happens because rails adds digest hashes to filenames
when compiling assets, e.g. img1.jpg becomes img1-dbu097452jf2v2.jpg.
When compiling its native css Rails transforms all urls and links to digested
versions, i.e. background-image: image-url(img1.jpg) becomes
background-image: url(img1-dbu097452jf2v2.jpg). However this doesn't happen for js and
css files compiled by webpack on the client side, because they don't use
image-url and asset-url and therefore assets fail to load.
Create symlinks of non-digested versions to digested versions when Rails assets compile.
The solution is implemented using assets:precompile after-hook. The assets for symlinking
are defined by config.symlink_non_digested_assets_regex in config/initializers/react_on_rails.rb.
To disable symlinks set this parameter to nil.