parse
among-stores
----
among-stores

parse
disabled
disabled,prev_path=foo
----
disabled
disabled,prev_path=foo

parse
path=/foo
path=/foo,prev_path=/bar
----
path=/foo
path=/foo,prev_path=/bar

parse
disabled,path=foo
among-stores,path=foo
among-stores,prev_path=foo
garbage
----
err: invalid disabled --wal-failover setting: disabled,path=foo expect disabled[,prev_path=<prev_path>]
err: invalid --wal-failover setting: among-stores,path=foo (possible values: disabled, among-stores, path=<path>)
err: invalid --wal-failover setting: among-stores,prev_path=foo (possible values: disabled, among-stores, path=<path>)
err: invalid --wal-failover setting: garbage (possible values: disabled, among-stores, path=<path>)
