Bug 18089 - All XSLT testing singleBranchMode = 0 fails to show even if install has...

Bug 18089 - All XSLT testing singleBranchMode = 0 fails to show even if install has only 1 branch

Due to the way it has been implemented, singleBranchMode is set to an
empty string rather than 0 if there is only one branch. This causes any
block that tests for singleBranchMOde to be 0 to never appear.

Test Plan:
1) Apply this patch set
2) prove t/XSLT.t

Signed-off-by: Jenny Schmidt <jschmidt@switchinc.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Mason James <mtj@kohaaloha.com>