Attempt to double free XML parser in ra_serf update editor

Hi,

Using Subversion 1.7.0-beta2, ra_serf.

It seems ra_serf attempts to free XML parser twice in some
circumstances. When performing switch between two branches I'm getting
the crash at:
> libsvn_ra-1.dll!XML_ParserFree(XML_ParserStruct * parser=0x0f2474b0) Line 1091 + 0x3f bytes C
         libsvn_ra-1.dll!svn_ra_serf__handle_xml_parser(serf_request_t *
request=0x12957b48, serf_bucket_t * response=0x12630868, void *
baton=0x12618dc8, apr_pool_t * pool=0x12702428) Line 1591 + 0x9
bytes C

Full stack trace is attached.

Unfortunately I cannot reproduce this issue, but it happens from time to time.

-- 
Ivan Zhakov