Cache is never repopulated when just the dependency changes

[NinoFloris]

Following the code and the debug messages we see the following

broccoli-eyeglass:persistent-cache Cannot cache app.scss. Reason: dependency changed:
src/frontend/scss/core/_box.scss +3ms
broccoli-eyeglass:persistent-cache Stacktrace: Error: dependency changed: src/frontend/scss/core/_box.scss

Looking at the code in broccoli_sass_compiler I see that this function call
https://github.com/sass-eyeglass/broccoli-eyeglass/blob/master/lib/broccoli_sass_compiler.js#L395

      dependencies.map(dep => this.checkDependency(srcDir, dep));

is right outside the try that sets error.key = key in its catch which means the check at handleCacheMiss https://github.com/sass-eyeglass/broccoli-eyeglass/blob/master/lib/broccoli_sass_compiler.js#L614

   return this.compileCssFile(details).
      then(result => {
        if (key) {
          return this.populateCache(key, details, result);
        }
      });

never triggers a repopulation of the cache, e.g. we're stuck forever as the cache won't ever be repopulated with rebuilt output.

Cache repopulation does work if I touch the entrypoint but we have 10 - 100 entrypoints for each of our customers, touching them all isn't an option as it would pollute our commits enormously.