Test suite: Make dsd-ssh work for installed-package tests

Previously it would say `perl dgit-ssh-dispatch' which causes perl to
look only in `.'.

diff --git a/tests/dsd-ssh b/tests/dsd-ssh
index 94a95827f2c0cfccbfd6a83708f17e56c885f1c6..d5df5aa67279548c4fedf344e0f894dcf99521df 100755 (executable)
--- a/tests/dsd-ssh
+++ b/tests/dsd-ssh
@@ -12,7 +12,7 @@ export SSH_ORIGINAL_COMMAND="$*"
 # undoes PERLLIB so that we rely on dgit-ssh-dispatch setting it
 # we have to compensate with -I so that dgit-ssh-dispatch finds Dgit.pm
 unset PERLLIB
-perl -I $DGIT_TEST_INTREE \
+${DGIT_TEST_INTREE+perl -I}$DGIT_TEST_INTREE \
 ${DGIT_SSH_DISPATCH_TEST-dgit-ssh-dispatch} -D $tmp
 
 : '))))))))))))))))))))))))))))))))))))))))'