From the traceback: the problem is that bzr-externals runs command `bzr add .bzrignore .bzrmeta/externals .bzrmeta/externals-snapshot` under the hood, and that command failed.
From the traceback: the problem is that bzr-externals runs command `bzr add .bzrignore .bzrmeta/externals .bzrmeta/ externals- snapshot` under the hood, and that command failed.