fixed fatal error in opPluginReleaseTask (fixes #377)
fixed fatal error in opPluginReleaseTask (fixes #377)

tejimaya/OpenPNE3,ShinichiU/OpenPNE3,balibali/KakiageSNS,balibali/KakiageSNS,ShinichiU/AuthFramework,openpne/OpenPNE3,isaosano/OpenPNE3,tejimaya/OpenPNE3,C-nakajima/OpenPNE3,C-nakajima/OpenPNE3,kashiwasan/symfony-advanced,ShinichiU/OpenPNE3,upsilon/OpenPNE3,ShinichiU/OpenPNE3_with_webInstaller,tejima/OP3PKG,nishizoe/OpenPNE3,ShinichiU/OpenPNE3_with_webInstaller,ShinichiU/OpenPNE3,kashiwasan/symfony-advanced,tejima/testravis,ShinichiU/AuthFramework,C-nakajima/OpenPNE3,nishizoe/OpenPNE3,isaosano/OpenPNE3,ShinichiU/AuthFramework,nise-nabe/ppcon-sns,tejima/testravis,nise-nabe/ppcon-sns,tejima/OP3PKG,upsilon/OpenPNE3,upsilon/travis-test,tejima/testravis,isaosano/OpenPNE3,openpne/OpenPNE3,openpne/OpenPNE3,ShinichiU/OpenPNE3,C-nakajima/OpenPNE3,openpne/OpenPNE3,upsilon/travis-test,isaosano/OpenPNE3