List repos with starting prefix

Fix the NullPointException when a user visits "/test/" but only
"/test/project_a" and "/test/project_b" exist in Gerrit. It will
now list all projects starting with "test." This was implemented
already in Gitiles, but threw an NPE in this plugin before.

Change-Id: Ifeeca8c5eba81e9a3596d206648b7769a661a430
1 file changed