Repeated scans report inappropriate 'Failed to find any channels'

[Nigel]

HDHomeRun DVB on a Mac, r20465. Initial scan works beautifully, progress dialog reports 'Scan Progress: Found 35' and final popup 'Found 35 new non-conflicting DVB channels.'
However, after 'Insert All', any subsequent scan will report 'Failed to find any channels', which threw me for a while (I thought I had broken something in recent HDHR mods). To reduce confusion, I think we need something like this:

% svn diff libs/libmythtv/channelscan/channelimporter.cpp
Index: libs/libmythtv/channelscan/channelimporter.cpp
===================================================================
--- channelscan/channelimporter.cpp     (revision 20468)
+++ channelscan/channelimporter.cpp     (working copy)
@@ -33,11 +33,15 @@
         {
             MythPopupBox::showOkPopup(
                 gContext->GetMainWindow(), QObject::tr("Channel Importer"),
-                QObject::tr("Failed to find any channels"));
+                ChannelUtil::GetChannelCount()
+                ? QObject::tr("Failed to find any new channels!")
+                : QObject::tr("Failed to find any channels."));
         }
         else
         {
-            VERBOSE(VB_IMPORTANT, LOC + "No channels to process..");
+            VERBOSE(VB_IMPORTANT, LOC + (ChannelUtil::GetChannelCount()
+                                         ? "No new channels to process"
+                                         : "No channels to process.."));
         }
 
         return;

(with the count method still to be determined

[Nigel]

(In [20470]) Better "failure" message for scanner. Closes #6517