Sometimes show-externals will output a space between the -r and <revision>. This patch removes that space.
Somewhere during development the find_svn_branch_name function returned a tuple, so if no repo was found I returned a (None, None) tuple. After changing what the function returned when an svn repo is found, I must have forgotten to also change the return value in the case nothing is found.
Instead of just trying to find a (remote) branch called trunk and assuming we are tracking that branch, acually do some factual checking to find a remote branch. When working on e.g. a local branch based on a branch in the subversion repository, this will result in a more accurate listing of unpushed commits.
message "SVN repository location required as a command-line argument" if the $revision variable was empty.