Backport 0.14.x: is_complete_fast #2869

Job	Run time
Check Style	8s
Verify hyper.h is up to date	22s
features	52s
Test C API (FFI)	38s
Test with Miri	2m 5s
Check MSRV (1.63)	28s
Check deprecated on stable	21s
Check deprecated on beta	27s
Test stable on ubuntu-latest	1m 30s
Test stable on windows-latest	3m 38s
Test stable on macOS-latest	1m 31s
Test beta on ubuntu-latest	1m 32s
Test beta on windows-latest	2m 56s
Test beta on macOS-latest	1m 36s
Test nightly on ubuntu-latest	1m 39s
Test nightly on windows-latest	3m 15s
Test nightly on macOS-latest	1m 43s
Build docs	20s
CI is green	0s
	25m 1s

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