Macros should not generate a breakline

[ylacaute]

This code:

{%- macro test() -%}
  {%- set foo = "world" -%}{{- foo -}}
{%- endmacro -%}
hello: {{- test() -}}

generates this expected output:

hello: world

But this code:

{%- macro test() -%}
  {%- set foo = "world" -%}
  {{- foo -}}
{%- endmacro -%}
hello: {{- test() -}}

generates this unexpected output :

hello: 
  world

I thought by using {{- ... -}} it would remove any spaces and breaklines, before and after, but it does not. Is that really expected or a bug ?

Thank you