Forward JAVA_TOOL_OPTIONS to tests (if set)

Progress towards bazelbuild#1708

buildkite/bazelci.py

@@ -1217,9 +1217,10 @@ def execute_commands(
         os.environ["BAZELISK_USER_AGENT"] = "Bazelisk/BazelCI"
         test_env_vars.append("BAZELISK_USER_AGENT")
 
-        # Avoid "Network is unreachable" problems in Python tests due to IPv6
-        if os.getenv("SSL_CERT_FILE"):
-            test_env_vars.append("SSL_CERT_FILE")
+        # Avoid "Network is unreachable" errors in IPv6-only environments
+        for e in ('JAVA_TOOL_OPTIONS', 'SSL_CERT_FILE'):
+          if os.getenv(e):
+              test_env_vars.append(e)
 
         # We use one binary for all Linux platforms (because we also just release one binary for all
         # Linux versions and we have to ensure that it works on all of them).