Lint gives incorrect MissingPrefix error

[sdebruyn]

Steps to Reproduce

1. Create a Xamarin.Android project, set minimum API level to 24 and target API level to 27
2. Set build property AndroidLintEnabled to true
3. Add an XML resource where you have xmlns:app="http://schemas.android.com/apk/res-auto" in the root element
4. Add an element that uses this namespace:

<TextView
            android:id="@+id/tv_itemaccountability_line"
            android:layout_width="150dp"
            android:layout_height="wrap_content"
            android:layout_marginBottom="8dp"
            android:layout_marginStart="8dp"
            android:layout_marginTop="8dp"
            android:gravity="left|center"
            style="@style/AccountabilityItemTextView"
            app:MvxBind="Text Line"
            app:layout_constraintBottom_toTopOf="@+id/ln_itemaccountability_line"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

5. Build with target SignAndroidPackage (or just deploy)

Important side note:
My Android app project also references an Android library project.

Expected Behavior

No errors of type MissingPrefix

Actual Behavior

In the build log:

(My build configuration is Development)

obj/Development/obj/Development/res/layout/item_accountability.xml(1,559): error XA0103:  Unexpected namespace prefix "app" found for tag TextView [MissingPrefix] [/path/to/my/project.csproj]

Version Information

=== Visual Studio Enterprise 2017 for Mac ===

Version 7.6.10 (build 27)
Installation UUID: e1324239-09f8-4ef0-841d-818a176fdfbd
Runtime:
	Mono 5.12.0.309 (2018-02/39d89a335c8) (64-bit)
	GTK+ 2.24.23 (Raleigh theme)
	Xamarin.Mac 4.4.1.178 (master / eeaeb7e6)

	Package version: 512000309

=== NuGet ===

Version: 4.3.1.4445

=== .NET Core ===

Runtime: /usr/local/share/dotnet/dotnet
Runtime Versions:
	2.1.2
	2.1.1
	2.1.0
	2.0.7
	2.0.5
SDK: /usr/local/share/dotnet/sdk/2.1.302/Sdks
SDK Versions:
	2.1.302
	2.1.301
	2.1.300
	2.1.200
	2.1.4
MSBuild SDKs: /Library/Frameworks/Mono.framework/Versions/5.12.0/lib/mono/msbuild/15.0/bin/Sdks

=== Xamarin.Profiler ===

Version: 1.6.3
Location: /Applications/Xamarin Profiler.app/Contents/MacOS/Xamarin Profiler

=== Apple Developer Tools ===

Xcode 10.0 (14320.25)
Build 10A255

=== Xamarin.Mac ===

Version: 5.0.0.0 (Visual Studio Enterprise)
Hash: b40230c0
Branch: 
Build date: 2018-09-27 11:41:37-0400

=== Xamarin.iOS ===

Version: 12.0.0.15 (Visual Studio Enterprise)
Hash: 84552a46
Branch: xcode10
Build date: 2018-09-17 21:54:33-0400

=== Xamarin.Android ===

Version: 9.0.0.20 (Visual Studio Enterprise)
Android SDK: /Users/sam/Library/Android/sdk
	Supported Android versions:
		5.0 (API level 21)
		6.0 (API level 23)
		7.0 (API level 24)
		7.1 (API level 25)
		8.0 (API level 26)
		8.1 (API level 27)

SDK Tools Version: 26.1.1
SDK Platform Tools Version: 28.0.1
SDK Build Tools Version: 28.0.3

Java SDK: /usr
java version "1.8.0_172"
Java(TM) SE Runtime Environment (build 1.8.0_172-b11)
Java HotSpot(TM) 64-Bit Server VM (build 25.172-b11, mixed mode)

Android Designer EPL code available here:
https://github.com/xamarin/AndroidDesigner.EPL

=== Xamarin Inspector ===

Version: 1.4.3
Hash: db27525
Branch: 1.4-release
Build date: Mon, 09 Jul 2018 21:20:18 GMT
Client compatibility: 1

=== Build Information ===

Release ID: 706100027
Git revision: 94dbd4d35daaa5a2ff6a51c3fd5cbb2308bd83ea
Build date: 2018-10-18 16:34:31+00
Build branch: release-7.6
Xamarin extensions: 3a9afc960ba73e5862829e8a0cd9369bcca43d70

=== Operating System ===

Mac OS X 10.14.0
Darwin 18.0.0 Darwin Kernel Version 18.0.0
    Wed Aug 22 20:13:40 PDT 2018
    root:xnu-4903.201.2~1/RELEASE_X86_64 x86_64

=== Enabled user installed extensions ===

Android Signature Tool 2.1.2
Gist Ide Information 1.1.0
MSBuild Editor 2.0.4
NuGet Package Explorer 0.2
NuGet Package Management Extensions 0.13
xUnit.NET 2 testing framework support 0.7.5

Log File

See above.