Fix an override_module bug.

proptools.PrependProperties doesn't replace a pointer when both the src
and the dst have one. This prevented override_module from overriding
simple value pointer properties when the base module has existing
values. It turns out this was why the name property needed to be
overwritten manually.

Bug: 122957760
Test: app_test.go
Change-Id: I3302287c31a560422548c22fade95261ddbe606a
diff --git a/java/app_test.go b/java/app_test.go
index 781fdff..1f6297c 100644
--- a/java/app_test.go
+++ b/java/app_test.go
@@ -877,6 +877,7 @@
 		android_app {
 			name: "foo",
 			srcs: ["a.java"],
+			certificate: "expiredkey",
 			overrides: ["baz"],
 		}
 
@@ -909,7 +910,7 @@
 		{
 			variantName: "android_common",
 			apkPath:     "/target/product/test_device/system/app/foo/foo.apk",
-			signFlag:    "build/target/product/security/testkey.x509.pem build/target/product/security/testkey.pk8",
+			signFlag:    "build/target/product/security/expiredkey.x509.pem build/target/product/security/expiredkey.pk8",
 			overrides:   []string{"baz"},
 			aaptFlag:    "",
 		},
@@ -923,7 +924,7 @@
 		{
 			variantName: "baz_android_common",
 			apkPath:     "/target/product/test_device/system/app/baz/baz.apk",
-			signFlag:    "build/target/product/security/testkey.x509.pem build/target/product/security/testkey.pk8",
+			signFlag:    "build/target/product/security/expiredkey.x509.pem build/target/product/security/expiredkey.pk8",
 			overrides:   []string{"baz", "foo"},
 			aaptFlag:    "--rename-manifest-package org.dandroid.bp",
 		},