Temporarily work around AppVeyor CI issues
diff --git a/appveyor.yml b/appveyor.yml
index 4c4676d..39c6a18 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -1,4 +1,24 @@
environment:
+
+ # At the time this was added AppVeyor was having troubles with checking
+ # revocation of SSL certificates of sites like static.rust-lang.org and what
+ # we think is crates.io. The libcurl HTTP client by default checks for
+ # revocation on Windows and according to a mailing list [1] this can be
+ # disabled.
+ #
+ # The `CARGO_HTTP_CHECK_REVOKE` env var here tells cargo to disable SSL
+ # revocation checking on Windows in libcurl. Note, though, that rustup, which
+ # we're using to download Rust here, also uses libcurl as the default backend.
+ # Unlike Cargo, however, rustup doesn't have a mechanism to disable revocation
+ # checking. To get rustup working we set `RUSTUP_USE_HYPER` which forces it to
+ # use the Hyper instead of libcurl backend. Both Hyper and libcurl use
+ # schannel on Windows but it appears that Hyper configures it slightly
+ # differently such that revocation checking isn't turned on by default.
+ #
+ # [1]: https://curl.haxx.se/mail/lib-2016-03/0202.html
+ RUSTUP_USE_HYPER: 1
+ CARGO_HTTP_CHECK_REVOKE: false
+
matrix:
- TARGET: x86_64-pc-windows-msvc
- TARGET: i686-pc-windows-msvc
