Merge branch 'jk/maint-http-half-auth-push' into maint-1.7.11

Pushing to smart HTTP server with recent Git fails without having the username in the URL to force authentication, if the server is configured to allow GET anonymously, while requiring authentication for POST. * jk/maint-http-half-auth-push: http: prompt for credentials on failed POST http: factor out http error code handling t: test http access to "half-auth" repositories t: test basic smart-http authentication t/lib-httpd: recognize */smart/* repos as smart-http t/lib-httpd: only route auth/dumb to dumb repos t5550: factor out http auth setup t5550: put auth-required repo in auth/dumb