cmd/gomvpkg: fix import rewrites for top-level moved package

The top-level moved package was skipped when doing import rewrites.
Don't skip that package.

Fixes #9811

Change-Id: I1c524ed44606586b5231e5adb6168079aa0e0228
Reviewed-on: https://go-review.googlesource.com/4470
Reviewed-by: Alan Donovan <adonovan@google.com>

refactor/rename/mvpkg.go

@@ -255,12 +255,8 @@ func (m *mover) move() error {
 		}
 	}
 
-	// For each affected package, rewrite all imports of the package to
-	// use the new import path.
+	// Update import paths for all imports by affected packages.
 	for ap := range m.affectedPackages {
-		if ap == m.from {
-			continue
-		}
 		info, ok := m.iprog.Imported[ap]
 		if !ok {
 			log.Fatalf("unexpected: package %s is not in import map", ap)

refactor/rename/mvpkg_test.go

@@ -182,6 +182,31 @@ type T int
 				"/go/src/bar/sub/0.go": `package sub; type T int`,
 			},
 		},
+
+		// References into subpackages
+		{
+			ctxt: fakeContext(map[string][]string{
+				"foo":   {`package foo; import "foo/a"; var _ a.T`},
+				"foo/a": {`package a; type T int`},
+				"foo/b": {`package b; import "foo/a"; var _ a.T`},
+			}),
+			from: "foo", to: "bar",
+			want: map[string]string{
+				"/go/src/bar/0.go": `package bar
+
+import "bar/a"
+
+var _ a.T
+`,
+				"/go/src/bar/a/0.go": `package a; type T int`,
+				"/go/src/bar/b/0.go": `package b
+
+import "bar/a"
+
+var _ a.T
+`,
+			},
+		},
 	}
 
 	for _, test := range tests {