fix(@angular-devkit/core): detect mingw terminal as color capable (#11834)

restoring color to git-bash users under windows

Fixes #11833

Author: bedag-moo

packages/angular_devkit/core/src/terminal/caps.ts

@@ -77,11 +77,11 @@ const ciVars = ['TRAVIS', 'CIRCLECI', 'APPVEYOR', 'GITLAB_CI'];
 
 
 function _getColorLevel(stream: Socket): number {
-  if (stream && !stream.isTTY) {
+  if (stream && !stream.isTTY && !_env.MSYSTEM) {
     return 0;
   }
 
-  if (_platform.startsWith('win32')) {
+  if (_platform.startsWith('win32') && !_env.MSYSTEM) {
     // Node.js 7.5.0 is the first version of Node.js to include a patch to
     // libuv that enables 256 color output on Windows. Anything earlier and it
     // won't work. However, here we target Node.js 8 at minimum as it is an LTS