Ceph - QEMU crash when Ceph pool pg_num is changed

Issue

When changing pg_num on a Ceph pool, QEMU VMs using a PG that is modified by the pg_num change operation die a horrible death:

osd/osd_types.cc: In function 'bool pg_t::is_split(unsigned int, unsigned int, 
std::set<pg_t>*) const' thread 7fd5e7fff700 time 2015-08-20 15:38:42.272380 
osd/osd_types.cc: 459: FAILED assert(m_seed < old_pg_num) 
 ceph version 0.94.2 (5fb85614ca8f354284c713a2f9c610860720bbf3) 
 1: (()+0x15376b) [0x7fd5fd94576b] 
 2: (()+0x222f11) [0x7fd5fda14f11] 
 3: (()+0x222fed) [0x7fd5fda14fed] 
 4: (()+0xc5379) [0x7fd5fd8b7379] 
 5: (()+0xdc4bc) [0x7fd5fd8ce4bc] 
 6: (()+0xdcd0a) [0x7fd5fd8ced0a] 
 7: (()+0xde272) [0x7fd5fd8d0272] 
 8: (()+0xe3fef) [0x7fd5fd8d5fef] 
 9: (()+0x2c3ba9) [0x7fd5fdab5ba9] 
 10: (()+0x2f15cd) [0x7fd5fdae35cd] 
 11: (()+0x8182) [0x7fd5f946c182] 
 12: (clone()+0x6d) [0x7fd5f919947d]

I found a Ceph bug (http://tracker.ceph.com/issues/10399) that is the exact issue and it looks like a fix was just merged to master. This ticket is to express our interest in seeing this quickly backported to Hammer.