I am getting the XML DOM Node from WriterStreamMetadata by calling getAsTree() passing the standard metadata format name. I am trying to merge the same node with the same metadata tree by calling the following methods:
metaData.reset();
metaData.mergeTree(std metadata format name, streamNode);
mergeTree() is throwing an IIOInvalidTreeException saying BitsPerSample attribute value is incorrect.

Here is the exception:
javax.imageio.metadata.IIOInvalidTreeException: Bad value for BitsPerSample attribute value!
at com.sun.imageio.plugins.gif.GIFMetadata.fatal(GIFMetadata.java:34)
at com.sun.imageio.plugins.gif.GIFMetadata.getIntAttribute(GIFMetadata.java:97)
at com.sun.imageio.plugins.gif.GIFWritableStreamMetadata.mergeStandardTree(GIFWritableStreamMetadata.java:184)
at com.sun.imageio.plugins.gif.GIFWritableStreamMetadata.mergeTree(GIFWritableStreamMetadata.java:56)
at WriterStreamMetadataTest.<init>(WriterStreamMetadataTest.java:59)
at WriterStreamMetadataTest.main(WriterStreamMetadataTest.java:117)

This is reproducible only with the following PIT build (b51) and not reproducible with b49. This is reproducible on all the platforms. This is not reproducible for other image formats.

I have attached a sample test. Execute the sample test as follows:
'java WriterStreamMetadataTest gif merge'
If you see the exception on the console, the bug is reproduced.