Checking out a thorn before the flesh creates the arrangements directory. When checking out the flesh (which contains this directory) an error occurs:
svn: Failed to add directory 'arrangements': an unversioned directory of the same name already exists
Usually, this does not happen as the flesh is mentioned first in thornlists. However, when using parallel checkouts it might actually be the case (and did happen for me). Running the same command a second time didn't produce this problem, which confirms that this is very much timing-dependent.
Possible solutions: 1) A notion to tell GetComponents about dependencies 2) A notion to tell Getcomponents about 'breakpoints', a poor-mans version of 1) 3) Removing the 'arrangements' directory from the flesh repository