Fix compiler crash from `match` with extra parens around `let` in tuple #2876

Job	Run time
Lint bash, docker, markdown, and yaml	1m 44s
Validate GNU Docker image builds	42s
Validate GNU Docker release image builds	30s
Validate musl Docker image builds	20s
Validate musl Docker release image builds	20s
Validate Windows Docker image builds	9m 49s
Validate Windows Docker release image builds	9m 53s
aarch64 Linux glibc	18m 21s
arm64 Apple Darwin	13m 42s
armhf Linux glibc	28m 14s
arm Linux glibc	29m 25s
riscv64 Linux glibc	23m 14s
Verify CHANGELOG is valid	5s
x86-64 Linux glibc	21m 5s
x86-64 Linux musl	23m 40s
x86-64 Apple Darwin	24m 15s
x86-64 Windows MSVC	38m 19s
use dtrace	20m 50s
use pool_memalign	25m 39s
use runtimestats	22m 15s
use pool_memalign,address_sanitizer,undefined_behavior_sanitizer	1h 36m 46s
	6h 49m 8s

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