Ember build adds read permission to some files but not others

In my Ember.js project, I have the following files:

public/img/pixels.png 0640
public/img/vector.svg 0640

After doing ember build -prod in a Docker container, I have the following files:

img/pixels-d72816e93259890d380ddf05acb748e7.png 0644
img/vector.svg 0640

Notice how the hashed file changed from 0640 to 0644.

Now on this Ember app, all references to pixels.png work fine, but references to vector.svg result in unavailable images.

What causes Ember to add the read bit for some, but not others? How can I force this to happen to all files from public? Shouldn't Ember do this automatically? (e.g. is this a bug?)