gdal merge tool: make sure -a_nodata is only added with gdal>=1.9

Author: etiennesky

python/plugins/GdalTools/tools/doMerge.py

@@ -147,8 +147,9 @@ def getArguments(self):
       if self.noDataCheck.isChecked():
         arguments.append("-n")
         arguments.append(str(self.noDataSpin.value()))
-        arguments.append("-a_nodata")
-        arguments.append(str(self.noDataSpin.value()))
+        if Utils.GdalConfig.versionNum() >= 1900:
+          arguments.append("-a_nodata")
+          arguments.append(str(self.noDataSpin.value()))
       if self.separateCheck.isChecked():
         arguments.append("-separate")
       if self.pctCheck.isChecked():