bash_completion update for mergeinfo --show-revs option.
bash_completion update for mergeinfo --show-revs option.

* tools/client-side/bash_completion: handle --show-revs argument values

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion