Fix a bug in format string found by code analysis.
Fix a bug in format string found by code analysis.

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