Multiple sheet instances broken with SCH_IO_MANAGER

When building with -DUSE_SCH_IO_MANAGER=ON, multiple instances of the same sheet are broken. Edits made to one instance do not apply to the other instances of that sheet, and the sheet appears to be written once per instance as well, meaning the edits are totally clobbered at save if they're not in the last one written.

Application: kicad
Version: (2016-07-22 BZR 6991, Git 146a78a)-product, debug build
Libraries: wxWidgets 3.0.2
           libcurl/7.49.1 OpenSSL/1.0.2h zlib/1.2.8 libidn/1.32 libssh2/1.7.0
Platform: Linux 4.6.4-1-ARCH x86_64, 64 bit, Little endian, wxGTK
- Build Info -
wxWidgets: 3.0.2 (wchar_t,wx containers,compatible with 2.8)
Boost: 1.60.0
Curl: 7.49.1
KiCad - Compiler: GCC 6.1.1 with C++ ABI 1010
        Settings: USE_WX_GRAPHICS_CONTEXT=OFF
                  USE_WX_OVERLAY=OFF
                  KICAD_SCRIPTING=ON
                  KICAD_SCRIPTING_MODULES=ON
                  KICAD_SCRIPTING_WXPYTHON=ON
                  USE_FP_LIB_TABLE=HARD_CODED_ON
                  BUILD_GITHUB_PLUGIN=ON