[Core] Fixes #655. Downgrade a match-match on the command line version specifier when there are no packages at all of that name, to a warning. It's essentially redundant, and thus ignored, and not worthy of an error (and the test harness fails in some cases with this)

Author: markfinal

Bam.Core/Package/PackageUtilities.cs

@@ -448,6 +448,11 @@ private static void
             {
                 var matches = rootNode.MatchingPackages(specifier.First());
                 var matchingVersions = matches.Select(item => item.Version);
+                if (!matchingVersions.Any())
+                {
+                    Log.Info($"Warning: Command line version specifier --{specifier.First()}.version={specifier.Last()} is redundant. Ignoring.");
+                    continue;
+                }
                 if (!matchingVersions.Contains(specifier.Last()))
                 {
                     var message = new System.Text.StringBuilder();

Changelog.txt

@@ -2,7 +2,7 @@
 
 04-Sep-2019 Fixes #654. Cannot use macros in 'ClCompile Include="path"' style .vcxproj elements, as it's not guaranteed to work. See https://docs.microsoft.com/en-us/cpp/build/reference/vcxproj-file-structure?view=vs-2015.
 
-04-Sep-2019 Fixes #655. Fixed regression that specifying a package version on the command line that did not match any package versions in the definition file was silently ignored.
+04-Sep-2019 Fixes #655. Fixed regression that specifying a package version on the command line that did not match any package versions in the definition file was silently ignored. If there are no packages of that name in the definition file, this is only a warning, otherwise, it is an error.
 
 01-Sep-2019 Fixes #650. Updated the following Nugets:
 * Microsoft.Extensions.Configuration.EnvironmentVariables to 2.2.4