Error in gsi-ssh and ssh on Mac 10.5: percent_expand: NULL replacement

I found this error while trying to log onto the TeraGrid ("Tara Grid") with gsissh (google "teragrid single sign on" for context).

percent_expand: NULL replacement

Apparently this is a well-known bug with Mac 10.5's ssh. The workaround is to append "-i ~/.ssh/id_rsa" or "-i ~/.ssh/id_dsa" to the command line, like so:

gsissh login-hg.ncsa.teragrid.org -i ~/.ssh/id_rsa

I got this from http://www.nabble.com/ssh%3A-percent_expand%3A-NULL-replacement-to13439207.html