Fix #919 - file locking exception sometimes seen when testing upload package with local file system.
Fix #919 - file locking exception sometimes seen when testing upload package with local file system.

JetBrains/ReSharperGallery,mtian/SiteExtensionGallery,ScottShingler/NuGetGallery,grenade/NuGetGallery_download-count-patch,grenade/NuGetGallery_download-count-patch,JetBrains/ReSharperGallery,mtian/SiteExtensionGallery,projectkudu/SiteExtensionGallery,KuduApps/NuGetGallery,KuduApps/NuGetGallery,KuduApps/NuGetGallery,ScottShingler/NuGetGallery,JetBrains/ReSharperGallery,grenade/NuGetGallery_download-count-patch,ScottShingler/NuGetGallery,projectkudu/SiteExtensionGallery,KuduApps/NuGetGallery,projectkudu/SiteExtensionGallery,mtian/SiteExtensionGallery,skbkontur/NuGetGallery,skbkontur/NuGetGallery,skbkontur/NuGetGallery,KuduApps/NuGetGallery