Appveyor tests are flaky (Cargo fails to download dependencies)

[qmonnet]

Appveyor runs often fails with:

[...]

C:\projects\rbpf>cargo test -vv  
    Updating crates.io index
 Downloading crates ...
warning: spurious network error (2 tries remaining): [35] SSL connect error (schannel: next InitializeSecurityContext failed: SEC_E_ILLEGAL_MESSAGE (0x80090326) - This error usually occurs when a fatal SSL/TLS alert is received (e.g. handshake failed). More detail may be available in the Windows System event log.)
warning: spurious network error (2 tries remaining): [35] SSL connect error (schannel: next InitializeSecurityContext failed: SEC_E_ILLEGAL_MESSAGE (0x80090326) - This error usually occurs when a fatal SSL/TLS alert is received (e.g. handshake failed). More detail may be available in the Windows System event log.)
warning: spurious network error (2 tries remaining): [35] SSL connect error (schannel: next InitializeSecurityContext failed: SEC_E_ILLEGAL_MESSAGE (0x80090326) - This error usually occurs when a fatal SSL/TLS alert is received (e.g. handshake failed). More detail may be available in the Windows System event log.)
warning: spurious network error (2 tries remaining): [35] SSL connect error (schannel: next InitializeSecurityContext failed: SEC_E_ILLEGAL_MESSAGE (0x80090326) - This error usually occurs when a fatal SSL/TLS alert is received (e.g. handshake failed). More detail may be available in the Windows System event log.)
warning: spurious network error (2 tries remaining): [35] SSL connect error (schannel: next InitializeSecurityContext failed: SEC_E_ILLEGAL_MESSAGE (0x80090326) - This error usually occurs when a fatal SSL/TLS alert is received (e.g. handshake failed). More detail may be available in the Windows System event log.)
warning: spurious network error (2 tries remaining): [35] SSL connect error (schannel: next InitializeSecurityContext failed: SEC_E_ILLEGAL_MESSAGE (0x80090326) - This error usually occurs when a fatal SSL/TLS alert is received (e.g. handshake failed). More detail may be available in the Windows System event log.)
warning: spurious network error (2 tries remaining): [35] SSL connect error (schannel: next InitializeSecurityContext failed: SEC_E_ILLEGAL_MESSAGE (0x80090326) - This error usually occurs when a fatal SSL/TLS alert is received (e.g. handshake failed). More detail may be available in the Windows System event log.)
warning: spurious network error (1 tries remaining): [35] SSL connect error (schannel: next InitializeSecurityContext failed: SEC_E_ILLEGAL_MESSAGE (0x80090326) - This error usually occurs when a fatal SSL/TLS alert is received (e.g. handshake failed). More detail may be available in the Windows System event log.)
warning: spurious network error (1 tries remaining): [35] SSL connect error (schannel: next InitializeSecurityContext failed: SEC_E_ILLEGAL_MESSAGE (0x80090326) - This error usually occurs when a fatal SSL/TLS alert is received (e.g. handshake failed). More detail may be available in the Windows System event log.)
warning: spurious network error (1 tries remaining): [35] SSL connect error (schannel: next InitializeSecurityContext failed: SEC_E_ILLEGAL_MESSAGE (0x80090326) - This error usually occurs when a fatal SSL/TLS alert is received (e.g. handshake failed). More detail may be available in the Windows System event log.)
warning: spurious network error (1 tries remaining): [35] SSL connect error (schannel: next InitializeSecurityContext failed: SEC_E_ILLEGAL_MESSAGE (0x80090326) - This error usually occurs when a fatal SSL/TLS alert is received (e.g. handshake failed). More detail may be available in the Windows System event log.)
warning: spurious network error (1 tries remaining): [35] SSL connect error (schannel: next InitializeSecurityContext failed: SEC_E_ILLEGAL_MESSAGE (0x80090326) - This error usually occurs when a fatal SSL/TLS alert is received (e.g. handshake failed). More detail may be available in the Windows System event log.)
warning: spurious network error (1 tries remaining): [35] SSL connect error (schannel: next InitializeSecurityContext failed: SEC_E_ILLEGAL_MESSAGE (0x80090326) - This error usually occurs when a fatal SSL/TLS alert is received (e.g. handshake failed). More detail may be available in the Windows System event log.)
warning: spurious network error (1 tries remaining): [35] SSL connect error (schannel: next InitializeSecurityContext failed: SEC_E_ILLEGAL_MESSAGE (0x80090326) - This error usually occurs when a fatal SSL/TLS alert is received (e.g. handshake failed). More detail may be available in the Windows System event log.)
error: failed to download from `https://crates.io/api/v1/crates/json/0.11.15/download`
Caused by:
  [35] SSL connect error (schannel: next InitializeSecurityContext failed: SEC_E_ILLEGAL_MESSAGE (0x80090326) - This error usually occurs when a fatal SSL/TLS alert is received (e.g. handshake failed). More detail may be available in the Windows System event log.)
C:\projects\rbpf>if 101 NEQ 0 exit 1 
Command exited with code 1

Best related resource I could find is rust-lang/cargo#9788 - But if I read correctly, this should be fixed with recent cargo versions (1.55+, we're using 1.64+), so I'm not sure what's causing those flakes and how to fix them. Any suggestion welcome.

[qmonnet]

It looks like they've been behaving better, recently. Maybe something fixed on Appveyor's or crates.io's end?