Architect#scheduleBuilder or context.scheduleBuilder results in incorrect target on context

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🐞 Bug report

Command (mark with an x)

• new
• build
• serve
• test
• e2e
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• lint
• extract-i18n
• run
• config
• help
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Is this a regression?

Not that I know of

Description

If a builder is executed via architect.scheduleBuilder, that builder is passed a context that doesn't match the declared interface in typescript. The same happens when using context.scheduleBuilder if no target is passed via the scheduleOptions.

console.log(context.target);
// logs {project: undefined, target: undefined, configuration: undefined}
// but type is {project: string, target: string, configuration?: string} | undefined

🔬 Minimal Reproduction

Run yarn bazel test //packages/angular_devkit/architect:architect_test with the following patch:

diff --git a/packages/angular_devkit/architect/src/index_spec.ts b/packages/angular_devkit/architect/src/index_spec.ts
index 57d76c5a6..bbd59b3fc 100644
--- a/packages/angular_devkit/architect/src/index_spec.ts
+++ b/packages/angular_devkit/architect/src/index_spec.ts
@@ -36,10 +36,12 @@ describe('architect', () => {
 
     options = {};
     called = 0;
-    testArchitectHost.addBuilder('package:test', createBuilder(async o => {
+    testArchitectHost.addBuilder('package:test', createBuilder(async (o, ctx) => {
       called++;
       options = o;
 
+      expect(ctx.target != null && ctx.target.target == null).toBe(false);
+
       return new Promise<BuilderOutput>(resolve => {
         setTimeout(() => resolve({ success: true }), 10);
       });

🔥 Exception or Error

Failures:
1) architect runs builders parallel
  Message:
    Expected true to be false.
  Stack:
    Error: Expected true to be false.
        at 
        at packages/angular_devkit/architect/src/index_spec.ts:43:63
        at onInput (packages/angular_devkit/architect/src/create-builder.ts:201:20)
        at SafeSubscriber._next (packages/angular_devkit/architect/src/create-builder.ts:87:17)

🌍 Your Environment

Master branch on this repo

Anything else relevant?