I have a png file added to the app.json appCache object:

    "appCache": {
         * List of items in the CACHE MANIFEST section
        "cache": [
This worked in previous sencha cmd versions, but now it throws an error:

[DEBUG]		generating new built index.html
[INFO ]		Embedded microloader into index.html
[INFO ]		Generating appcache
[INFO ]		Generating checksum for appCache item: index.html
[INFO ]		Generating checksum for appCache item: images/my-image.png
[ERROR]		com.sencha.exceptions.BasicException: The following error occurred while executing this line:
[ERROR]		/Users/shiller/Work/myapp/.sencha/app/build-impl.xml:120: javax.script.ScriptException: sun.org.mozilla.javascript.internal.WrappedException: Wrapped com.sencha.exceptions.BasicException: failed calculating SHA-1 hash (<Unknown source>#619) in <Unknown source> at line number 619
[ERROR]			at com.sencha.exceptions.BasicException.wrap(BasicException.java:43)
Removing the image from the app.json file allows the build process to run without errors.

(I'm using ST 2.1 RC2)