(test driver) editrc function buglet

Till now I did not have an RC var whose name was a prefix of another
valid RC var, so I never noticed that editrc would set the longer one
also when you set the shorter one.

Fixed

t/test-driver.sh

@@ -36,7 +36,7 @@ capture() { cf=$1; shift; "$@" >& $TESTDIR/$cf; }
 
 editrc() {
     scp gitolite-test@localhost:.gitolite.rc ~/junk >/dev/null
-    perl -pi -e "print STDERR if not /^#/ and /$1/ and s/=.*/= $2;/" ~/junk
+    perl -pi -e "print STDERR if not /^#/ and /$1\b/ and s/=.*/= $2;/" ~/junk
     scp ~/junk gitolite-test@localhost:.gitolite.rc >/dev/null
 }