Fix buildRustPackage edge cases

1. When multiple versions of the same package are required
   $revs is an array.
2. When cargo fetch is run it usually doesn't need a network
   connection. But when it does SSL_CERT_FILE isn't set.

pkgs/build-support/rust/default.nix

@@ -44,6 +44,7 @@ in stdenv.mkDerivation (args // {
 
     export CARGO_HOME="$(realpath deps)"
     export RUST_LOG=${logLevel}
+    export SSL_CERT_FILE=${cacert}/etc/ssl/certs/ca-bundle.crt
 
     # Let's find out which $indexHash cargo uses for file:///dev/null
     (cd $sourceRoot && cargo fetch &>/dev/null) || true

pkgs/build-support/rust/fetch-cargo-deps

@@ -147,7 +147,7 @@ EOF
             done
 
             # Create ad-hoc branches for the revs we need
-            echo "$revs" | while read rev; do
+            echo "$revs" | tr " " "\n" | while read -d " " rev; do
                 echo "Creating git branch b_$rev $rev"
                 git branch b_$rev $rev
             done