Added a check for extension of a filename to the gif loader, since it looks

like the isn't reconginizing rgb files as not being gif.

src/osgPlugins/gif/ReaderWriterGIF.cpp

@@ -326,6 +326,9 @@ class ReaderWriterGIF : public osgDB::ReaderWriter
         virtual ReadResult readImage(const std::string& fileName, const osgDB::ReaderWriter::Options*)
         {
 
+            std::string ext = osgDB::getFileExtension(fileName);
+            if (!acceptsExtension(ext)) return ReadResult::FILE_NOT_HANDLED;
+
             unsigned char *imageData = NULL;
             int width_ret;
             int height_ret;