Fix the DB schema version check. Backports [24820] from trunk.

git-svn-id: http://svn.mythtv.org/svn/branches/release-0-23-fixes@24821 7dbf422c-18fa-0310-86e9-fd20926502f2

mythtv/libs/libmyth/schemawizard.cpp

@@ -261,6 +261,11 @@ SchemaUpgradeWizard::PromptForUpgrade(const char *name,
         return MYTH_SCHEMA_USE_EXISTING;
 #endif
 
+    // Only back up the database if it's old/about to be upgraded
+    // (not if it's too new)
+    // or if a user is doing something they probably shouldn't ("expert mode")
+    if ((upgradeAllowed && (versionsBehind > 0)) || m_expertMode)
+        BackupDB();
 
     connections = CountClients() > 1;
     gui         = GetMythUI()->IsScreenSetup() && gContext->GetMainWindow();
@@ -314,6 +319,14 @@ SchemaUpgradeWizard::PromptForUpgrade(const char *name,
             return MYTH_SCHEMA_EXIT;
         }
 
+        if (versionsBehind < 0)
+        {
+            VERBOSE(VB_IMPORTANT, QString("Error: MythTV database has newer "
+                    "%1 schema (%2) than expected (%3).")
+                    .arg(name).arg(DBver).arg(m_newSchemaVer));
+            return MYTH_SCHEMA_ERROR;
+        }
+
         if (upgradeIfNoUI && validDBMS)
         {
             VERBOSE(VB_IMPORTANT, "Upgrading.");

mythtv/libs/libmythtv/dbcheck.cpp

@@ -476,13 +476,8 @@ bool UpgradeTVDatabaseSchema(const bool upgradeAllowed,
         return true;
     }
 
-    // An upgrade is likely. We do the backup first so that
-    // the UI can tell the user where the backup is located.
-    if (upgradeAllowed)
-        DBup->BackupDB();
-    else
-        VERBOSE(VB_IMPORTANT, "Not allowed to upgrade the database. "
-                              "Skipping backup.");
+    if (!upgradeAllowed)
+        VERBOSE(VB_IMPORTANT, "Not allowed to upgrade the database.");
 
     // Pop up messages, questions, warnings, et c.
     switch (DBup->PromptForUpgrade("TV", upgradeAllowed,