credential-cache: handle ECONNREFUSED gracefully #82

Job	Run time
config	7s
fuzz smoke test	33s
win+VS build	0s
almalinux-8 (almalinux:8)	10m 29s
linux32 (i386/ubuntu:focal)	9m 6s
debian-11 (debian:11)	9m 34s
linux-musl (alpine)	7m 36s
pedantic (fedora)	1m 47s
documentation	3m 59s
linux-asan-ubsan (ubuntu-latest)	31m 49s
linux-gcc (ubuntu-20.04)	10m 6s
linux-gcc-default (ubuntu-latest)	10m 24s
linux-leaks (ubuntu-latest)	32m 39s
linux-reftable (ubuntu-latest)	10m 57s
linux-reftable-leaks (ubuntu-latest)	33m 50s
linux-sha256 (ubuntu-latest)	10m 9s
linux-TEST-vars (ubuntu-20.04)	10m 14s
osx-clang (macos-13)	27m 14s
osx-gcc (macos-13)	27m 38s
osx-reftable (macos-13)	36m 58s
sparse	5m 28s
static-analysis	3m 56s
win build	4m 6s
win+VS test	0s
win test	0s
	4h 58m 39s

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