x/net/http2: many tests are flaky: Error while expecting an RSTStream frame: timeout waiting for frame

[dsnet]

https://storage.googleapis.com/go-build-log/0b1b6d4c/openbsd-amd64-gce58_f9489e71.log

--- FAIL: TestServer_Request_Reject_Pseudo_scheme_invalid (2.02s)
	server_test.go:475: Error while expecting an RSTStream frame: timeout waiting for frame
--- FAIL: TestServer_Request_Connect_InvalidPath (2.03s)
	server_test.go:475: Error while expecting an RSTStream frame: timeout waiting for frame
FAIL
FAIL	golang.org/x/net/http2	44.630s

[bradfitz]

/cc @tombergan

[bradfitz]

We're seeing this across the board on basically on all GOOS now.

[bradfitz]

Closed dup #18235. See some debugging notes there.

[bradfitz]

With @tombergan's new debugging,

https://build.golang.org/log/b8e6726f6ff2fecdaebc69ebbd16e2f3c34a7ea4

--- FAIL: TestServer_Rejects_HeadersSelfDependence (2.07s)
	server_test.go:510: Error while expecting an RSTStream frame: timeout waiting for frame
	server_test.go:229: Framer read log:
		2016-12-08 17:00:48.731964688 Framer 0x3a776c00: read SETTINGS len=18, settings: MAX_FRAME_SIZE=1048576, MAX_CONCURRENT_STREAMS=250, MAX_HEADER_LIST_SIZE=1048896
		2016-12-08 17:00:48.732088456 Framer 0x3a776c00: read SETTINGS flags=ACK len=0
	server_test.go:235: Framer write log:
		2016-12-08 17:00:48.700756846 Framer 0x3a776c00: wrote SETTINGS len=0
		2016-12-08 17:00:48.73199436 Framer 0x3a776c00: wrote SETTINGS flags=ACK len=0
		2016-12-08 17:00:48.732123435 Framer 0x3a776c00: wrote HEADERS flags=END_STREAM|END_HEADERS|PRIORITY stream=1 len=21
FAIL
FAIL	golang.org/x/net/http2	24.016s