See,
$ gometalinter --vendor --deadline 6m --disable-all --enable=megacheck ./...
pkg/tsdb/mssql/mssql_test.go:695:33:warning: do not pass a nil Context, even if a function permits it; pass context.TODO if you are unsure about which Context to use (SA1012) (megacheck)
pkg/tsdb/mysql/mysql_test.go:772:32:warning: do not pass a nil Context, even if a function permits it; pass context.TODO if you are unsure about which Context to use (SA1012) (megacheck)
pkg/tsdb/postgres/postgres_test.go:704:33:warning: do not pass a nil Context, even if a function permits it; pass context.TODO if you are unsure about which Context to use (SA1012) (megacheck)