Fix compiler crash from `match` with extra parens around `let` in tuple #2878

Job	Run time
Validate Windows Docker image builds	2m 11s
Validate GNU Docker image builds	32s
Lint bash, docker, markdown, and yaml	1m 41s
Validate GNU Docker release image builds	38s
Validate musl Docker release image builds	20s
Validate musl Docker image builds	20s
Validate Windows Docker release image builds	2m 19s
aarch64 Linux glibc	18m 14s
arm64 Apple Darwin	15m 26s
armhf Linux glibc	28m 1s
arm Linux glibc	27m 57s
riscv64 Linux glibc	23m 23s
Verify CHANGELOG is valid	13s
x86-64 Linux glibc	21m 3s
x86-64 Apple Darwin	26m 5s
x86-64 Windows MSVC	39m 14s
x86-64 Linux musl	24m 9s
use dtrace	20m 36s
use pool_memalign	23m 47s
use runtimestats	22m 3s
use pool_memalign,address_sanitizer,undefined_behavior_sanitizer	1h 35m 5s
	6h 33m 17s

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