credential-cache: handle ECONNREFUSED gracefully #5276

Job	Run time
config	4s
fuzz smoke test	48s
win build	6m 39s
win+VS build (arm64)	3m 44s
win+VS build (x64)	3m 43s
documentation	4m 58s
almalinux-8 (almalinux:8)	1m 31s
debian-11 (debian:11)	1m 41s
linux-musl (alpine)	1m 50s
pedantic (fedora)	1m 47s
linux32 (i386/ubuntu:focal)	2m 8s
sparse	3m 15s
static-analysis	3m 45s
linux-asan-ubsan (ubuntu-latest)	3m 36s
linux-gcc (ubuntu-20.04)	1m 35s
linux-gcc-default (ubuntu-latest)	2m 23s
linux-leaks (ubuntu-latest)	1m 10s
linux-reftable (ubuntu-latest)	1m 58s
linux-reftable-leaks (ubuntu-latest)	1m 2s
linux-sha256 (ubuntu-latest)	1m 45s
linux-TEST-vars (ubuntu-20.04)	1m 40s
osx-clang (macos-13)	1m 3s
osx-gcc (macos-13)	1m 35s
osx-reftable (macos-13)	1m 5s
win+VS test	0s
win test	0s
	54m 45s

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