Merge branch 'jk/maint-http-half-auth-fetch'

Merge branch 'jk/maint-http-half-auth-fetch'

Fixes fetch from servers that ask for auth only during the actual
packing phase. This is not really a recommended configuration, but it
cleans up the code at the same time.

* jk/maint-http-half-auth-fetch:
  remote-curl: retry failed requests for auth even with gzip
  remote-curl: hoist gzip buffer size to top of post_rpc