nesting [color] tags doesn't work properly

Nested color tags get only partially converted.

[color=#FF0000]this is red text [color=#0000FF]this is blue text[/color] this is the remaining red text[/color]

produces:
this is red text [color=#0000FF]this is blue text this is the remaining red text[/color]

a workaround is to use more tags, but the first version should work too.

[color=#FF0000]this is red text [/color][color=#0000FF]this is blue text[/color][color=#FF0000] this is the remaining red text[/color]

produces:
this is red text this is blue text this is the remaining red text