Concatenation with if conditions could be indented better

Consider to following output for `jsonnet fmt --indent 4 --string-style l `

```
local tcm = if (env.isDev) then [] else [] +
if (env.isDev || env.isStaging) then [] else [] +
[
'app',
];

local tcm2 = "a" + "b " +
"c";

local tcm3 = ["a"] + ["b "] +
["c"];

{
}

```

Once if conditions are involved with concatenations, it looks like jsonnet fmt does not indent correctly.