manifest: reset PackageInstaller to 6.0.1-r20 for now

Change-Id: I9a8ab22683d333b64e4bfc96aa431d2f67ee0476

default.xml

@@ -378,7 +378,7 @@
   <project path="packages/apps/OmniSwitch" name="android_packages_apps_OmniSwitch" remote="omnirom" revision="android-6.0" />
   <project path="packages/apps/OneTimeInitializer" name="platform/packages/apps/OneTimeInitializer" />
   <project path="packages/apps/OpenDelta" name="android_packages_apps_OpenDelta" remote="omnirom" revision="android-6.0" />
-  <project path="packages/apps/PackageInstaller" name="android_packages_apps_PackageInstaller" remote="omnirom" revision="android-6.0" />
+  <project path="packages/apps/PackageInstaller" name="android_packages_apps_PackageInstaller" remote="omnirom" revision="android-6.0.1_r20" />
   <project path="packages/apps/PerformanceControl" name="android_packages_apps_PerformanceControl" remote="omnirom" revision="android-6.0" />
   <project path="packages/apps/Phone" name="platform/packages/apps/Phone" groups="pdk-fs" />
   <project path="packages/apps/PhoneCommon" name="platform/packages/apps/PhoneCommon" />