I have the same problem.
Furthermore, I am the owner of the chained proxy that meteor connects to and I get this funny line in the access.log:
1441809073.817 0 22.214.171.124 TAG_NONE/400 4394 NONE error:invalid-request - HIER_NONE/- text/html
somehow when I put squid in full debug, I only see a funny request string when it tries to update a package:
Sorry, this project uses Meteor 126.96.36.199, which is not installed and could not be downloaded. Please check to make sure that you are online.
Downloading email@example.com... \
and I see:
reset: Request buffer is N
2015/09/09 16:31:13.817| HttpParser.cc(47) parseRequestFirstLine: parsing possible request: N
which actually reads as funny ASCII "┬ ┴ N "characters…
I also would like to know how meteor update works: protocol, tcp, udp, https, http, endpoint, etc.