V5 $theme-colors

Created by: NatachaH

Hi,

I just tried the new Bootstrap 5.0.0-alpha1 and when I wanted to add a new color to $theme-colors it override all the theme.

I compared the code with the v 4.5.0 and I found that in the file variables.scss the map-merge is missing.

In v4.5.0

$theme-colors: () !default;

$theme-colors: map-merge(
  (
    "primary":    $primary,
    "secondary":  $secondary,
    "success":    $success,
    "info":       $info,
    "warning":    $warning,
    "danger":     $danger,
    "light":      $light,
    "dark":       $dark
  ),
  $theme-colors
);

In V5

$theme-colors: (
  "primary":    $primary,
  "secondary":  $secondary,
  "success":    $success,
  "info":       $info,
  "warning":    $warning,
  "danger":     $danger,
  "light":      $light,
  "dark":       $dark
) !default;