Make ensureServers return properly if only one of -m or -b is specified.
Make ensureServers return properly if only one of -m or -b is specified.

mrdiegoa/ramcloud,matrix207/RAMCloud,Frank-Wu/RamCloud,jcarreira/ramcloud,IMCG/RamCloud,utah-scs/RAMCloud,rstutsman/RAMCloud,matrix207/RAMCloud,SMatsushi/RAMCloud,behnamm/cs244b_project,IMCG/RamCloud,utah-scs/RAMCloud,y-higuchi/ramcloud,mrdiegoa/ramcloud,y-higuchi/ramcloud,IMCG/RamCloud,y-higuchi/ramcloud,anirajk/RAMCloud,jcarreira/ramcloud,DavidLi2010/ramcloud,taschik/ramcloud,rstutsman/RAMCloud,rstutsman/RAMCloud,behnamm/cs244b_project,y-higuchi/ramcloud,jcarreira/ramcloud,alexandermerritt/ramcloud,SMatsushi/RAMCloud,alexandermerritt/ramcloud,SMatsushi/RAMCloud,DavidLi2010/ramcloud,IMCG/RamCloud,alexandermerritt/ramcloud,SMatsushi/RAMCloud,behnamm/cs244b_project,utah-scs/RAMCloud,jcarreira/ramcloud,rstutsman/RAMCloud,y-higuchi/ramcloud,SMatsushi/RAMCloud,jcarreira/ramcloud,jcarreira/ramcloud,matrix207/RAMCloud,mrdiegoa/ramcloud,y-higuchi/ramcloud,anirajk/RAMCloud,rstutsman/RAMCloud,utah-scs/RAMCloud,alexandermerritt/ramcloud,utah-scs/RAMCloud,anirajk/RAMCloud,Frank-Wu/RamCloud,mrdiegoa/ramcloud,matrix207/RAMCloud,jblomer/ramcloud,behnamm/cs244b_project,taschik/ramcloud,mrdiegoa/ramcloud,QingkaiLu/RAMCloud,Frank-Wu/RamCloud,Frank-Wu/RamCloud,jblomer/ramcloud,DavidLi2010/ramcloud,behnamm/cs244b_project,alexandermerritt/ramcloud,rstutsman/RAMCloud,jblomer/ramcloud,alexandermerritt/ramcloud,SMatsushi/RAMCloud,taschik/ramcloud,DavidLi2010/ramcloud,taschik/ramcloud,DavidLi2010/ramcloud,behnamm/cs244b_project,utah-scs/RAMCloud,anirajk/RAMCloud,taschik/ramcloud,QingkaiLu/RAMCloud,anirajk/RAMCloud,QingkaiLu/RAMCloud,jblomer/ramcloud,QingkaiLu/RAMCloud,IMCG/RamCloud,Frank-Wu/RamCloud,QingkaiLu/RAMCloud,jblomer/ramcloud,anirajk/RAMCloud,matrix207/RAMCloud,IMCG/RamCloud,jblomer/ramcloud,DavidLi2010/ramcloud,mrdiegoa/ramcloud,matrix207/RAMCloud,Frank-Wu/RamCloud,QingkaiLu/RAMCloud