BUG: io language port doesn't build

[trio@…]

bash-3.2$ sudo port install io
--->  Fetching Io
--->  Attempting to fetch Io-2007-03-21.tar.gz from http://io.urbanape.com/release/
--->  Verifying checksum(s) for Io
--->  Extracting Io
--->  Configuring Io
--->  Building Io with target -project osxvm.xcodeproj -target osxvm
Error: Target org.macports.build returned: shell command "cd /opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_ports_lang_Io/work/Io-2007-03-21 && make" returned error 2
Command output: cc -dynamiclib -flat_namespace -L../basekit/_build/dll _build/objs/*.o -o _build/dll/libgarbagecollector.dylib -lbasekit 
cp source/Collector.h source/CollectorMarker.h source/CollectorMarker_inline.h source/Collector_inline.h _build/headers
make -f Makefile.local all_begin 
cc tools/io2c.c -o tools/io2c
./tools/io2c VMCode IoState_doString_ io/A0_List.io io/A1_OperatorTable.io io/A2_Object.io io/A3_List.io io/A3_List_schwartzian.io io/A4_Exception.io io/Actor.io io/AddonLoader.io io/B_Sequence.io io/Block.io io/CFunction.io io/Date.io io/Debugger.io io/Directory.io io/DynLib.io io/File.io io/Map.io io/Message.io io/Number.io io/Sandbox.io io/Serialize.io io/System.io io/UnitTest.io io/Y_Path.io io/Z_CLI.io io/Z_Importer.io > source/IoVMInit.c
mkdir -p _build
mkdir -p _build/objs
mkdir -p _build/headers
mkdir -p _build/lib
mkdir -p _build/dll
make _build/lib/libiovm.a
cc -DINSTALL_PREFIX=\"/usr/local\" -O3 -g  -Wstrict-prototypes  -I. -I/source -I../basekit/_build/headers -I../coroutine/_build/headers -I../garbagecollector/_build/headers  -falign-loops=16 -fPIC -DBUILDING_IOVM_DLL  -c source/IoBlock.c -o _build/objs/IoBlock.o
In file included from source/IoState.h:19,
                 from source/IoObject_inline.h:13,
                 from source/IoObject.h:231,
                 from source/IoBlock.h:11,
                 from source/IoBlock.c:9:
source/IoCoroutine.h:13:18: error: Coro.h: No such file or directory
In file included from source/IoState.h:19,
                 from source/IoObject_inline.h:13,
                 from source/IoObject.h:231,
                 from source/IoBlock.h:11,
                 from source/IoBlock.c:9:
source/IoCoroutine.h:25: error: syntax error before 'Coro'
source/IoCoroutine.h:25: warning: no semicolon at end of struct or union
source/IoCoroutine.h:28: error: syntax error before '}' token
source/IoCoroutine.h:28: warning: data definition has no type or storage class
make[2]: *** [_build/objs/IoBlock.o] Error 1
make[1]: *** [all] Error 2
make: *** [vm] Error 2

Error: Status 1 encountered during processing.
bash-3.2$