duplicate dir creation is not giving any error

[princeparmar]

/zbox createdir --allocation 4157af127d56077124753022f00cf84fb09df87f66d6bc46f9a61a27d45ff851 --dirname test

if we execute createdir comand with same dir name then in database instead of giving an error it creates duplicate entries.

test | /test | 4157af127d56077124753022f00cf84fb09df87f66d6bc46f9a61a27d45ff851
test | /test | 4157af127d56077124753022f00cf84fb09df87f66d6bc46f9a61a27d45ff851
test | /test | 4157af127d56077124753022f00cf84fb09df87f66d6bc46f9a61a27d45ff851
test | /test | 4157af127d56077124753022f00cf84fb09df87f66d6bc46f9a61a27d45ff851
test | /test | 4157af127d56077124753022f00cf84fb09df87f66d6bc46f9a61a27d45ff851
test | /test | 4157af127d56077124753022f00cf84fb09df87f66d6bc46f9a61a27d45ff851
test | /test | 4157af127d56077124753022f00cf84fb09df87f66d6bc46f9a61a27d45ff851
test | /test | 4157af127d56077124753022f00cf84fb09df87f66d6bc46f9a61a27d45ff851
/ | / | 4157af127d56077124753022f00cf84fb09df87f66d6bc46f9a61a27d45ff851

[cnlangzi]

it is related to #329