don't catch OSErrors in finding git branch
don't catch OSErrors in finding git branch

I'm not sure why I wrote this this way originally. I can't think of a
situation where git fails and you want to continue execution here -- if
git itself fails, something is likely so borked that you don't want
these test results.

beobal/cassandra-dtest,bdeggleston/cassandra-dtest,spodkowinski/cassandra-dtest,carlyeks/cassandra-dtest,pcmanus/cassandra-dtest,riptano/cassandra-dtest,beobal/cassandra-dtest,iamaleksey/cassandra-dtest,stef1927/cassandra-dtest,spodkowinski/cassandra-dtest,snazy/cassandra-dtest,aweisberg/cassandra-dtest,iamaleksey/cassandra-dtest,stef1927/cassandra-dtest,blerer/cassandra-dtest,snazy/cassandra-dtest,pauloricardomg/cassandra-dtest,bdeggleston/cassandra-dtest,krummas/cassandra-dtest,blerer/cassandra-dtest,aweisberg/cassandra-dtest,mambocab/cassandra-dtest,thobbs/cassandra-dtest,riptano/cassandra-dtest,krummas/cassandra-dtest,mambocab/cassandra-dtest,thobbs/cassandra-dtest,pauloricardomg/cassandra-dtest,carlyeks/cassandra-dtest