Unable to set color to off via timew config

```
% timew config color off
Are you sure you want to change the value of 'color' from 'on' to 'off'? (yes/no) yes
Are you sure you want to change the value of 'color' from 'on' to 'off'? (yes/no) yes
Are you sure you want to change the value of 'color' from 'on' to 'off'? (yes/no) yes
Are you sure you want to change the value of 'color' from 'on' to 'off'? (yes/no) yes
Are you sure you want to change the value of 'color' from 'on' to 'off'? (yes/no) yes
Are you sure you want to change the value of 'color' from 'on' to 'off'? (yes/no) yes
Are you sure you want to change the value of 'color' from 'on' to 'off'? (yes/no) yes
Are you sure you want to change the value of 'color' from 'on' to 'off'? (yes/no) yes
Config file /Users/ignis/.timewarrior/timewarrior.cfg modified.
% timew config
color = on
[snip...]
% timew --version
1.4.3
```

It turns out it overwrote my `tag..color` configs:

```
define tags:
body:
color = off
fun:
color = off
lazy:
color = off
school:
color = off
sleep:
color = off
travel:
color = off
work:
color = off
```