net: TestFileConn/tcp failures

[gopherbot]

#!watchflakes
default <- pkg == "net" && test == "TestFileConn/tcp"

Issue created automatically to collect these failures.

Example (log):

=== RUN   TestFileConn/tcp
    file_test.go:107: file file+net tcp:127.0.0.1:50223->127.0.0.1:50222: protocol not supported
--- FAIL: TestFileConn/tcp (0.00s)

— watchflakes

[gopherbot]

Found new dashboard test flakes for:

#!watchflakes
default <- pkg == "net" && test == "TestFileConn/tcp"

2025-09-05 15:11 gotip-windows-amd64-race go@87e72769 net.TestFileConn/tcp (log)

=== RUN   TestFileConn/tcp
    file_test.go:107: file file+net tcp:127.0.0.1:50223->127.0.0.1:50222: protocol not supported
--- FAIL: TestFileConn/tcp (0.00s)

— watchflakes