I solved this problem by creating an empty "res" folder in the project in question.
In my case, the error was:
[2015-08-10 16:52:37 - picasso] ERROR: resource directory '/Users/me/MyProject/Dependencies/Lib/picasso/picasso/res' does not exist
There was no res folder, but after making an empty error, this error disappeared and my workspace was built again.
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