Update: if we use the Unity version of the runtime instead of the tk2d version, it works.
Here's a log from the crash:
[13-08-02 3:25:42 PM] Mario Progresivo: D/Unity (11650): Timed out. Continuing without host connection.
D/Unity (11650): Using monoOptions
debugger-agent=transport=dt_socket,embedding=1,defer=y,address=0.0.0.0:56827
W/libc (11650): WARNING: generic atexit() called from legacy shared library
F/libc (11650): bionic/libc/upstream-netbsd/libc/stdlib/bsearch.c:70: bsearch: assertion "key != NULL" failed
F/libc (11650): Fatal signal 11 (SIGSEGV) at 0xdeadbaad (code=1), thread 11667 (UnityMain)
[13-08-02 3:26:38 PM] Mario Progresivo: W/ActivityManager( 522): Force finishing activity com.DeNA.spineTest/com.unity3d.player.UnityPlayerNativeActivity
I/BootReceiver( 522): Copying /data/tombstones/tombstone_03 to DropBox (SYSTEM_TOMBSTONE)
W/InputDispatcher( 522): channel '42206ba0 com.DeNA.spineTest/com.unity3d.player.UnityPlayerNativeActivity (server)' ~ Consumer closed input channel or an error occurred. events=0x9
E/InputDispatcher( 522): channel '42206ba0 com.DeNA.spineTest/com.unity3d.player.UnityPlayerNativeActivity (server)' ~ Channel is unrecoverably broken and will be disposed!
D/Zygote ( 171): Process 11650 terminated by signal (11)
D/dalvikvm( 522): GC_FOR_ALLOC freed 2712K, 27% free 23109K/31360K, paused 78ms, total 78ms
W/InputDispatcher( 522): Attempted to unregister already unregistered input channel '42206ba0 com.DeNA.spineTest/com.unity3d.player.UnityPlayerNativeActivity (server)'
W/ActivityManager( 522): Exception thrown during pause
W/ActivityManager( 522): android.os.DeadObjectException
W/ActivityManager( 522): at android.os.BinderProxy.transact(Native Method)
W/ActivityManager( 522): at android.app.ApplicationThreadProxy.schedulePauseActivity(ApplicationThreadNative.java:635)
W/ActivityManager( 522): at com.android.server.am.ActivityStack.startPausingLocked(ActivityStack.java:990)
W/ActivityManager( 522): at com.android.server.am.ActivityStack.finishActivityLocked(ActivityStack.java:3834)
W/ActivityManager( 522): at com.android.server.am.ActivityStack.finishActivityLocked(ActivityStack.java:3766)
W/ActivityManager( 522): at com.android.server.am.ActivityManagerService.handleAppCrashLocked(ActivityManagerService.java:8344)
W/ActivityManager( 522): at com.android.server.am.ActivityManagerService.makeAppCrashingLocked(ActivityManagerService.java:8221)
W/ActivityManager( 522): at com.android.server.am.ActivityManagerService.crashApplication(ActivityManagerService.java:8900)
W/ActivityManager( 522): at com.android.server.am.ActivityManagerService.handleApplicationCrashInner(ActivityManagerService.java:8455)
W/ActivityManager( 522): at com.android.server.am.NativeCrashListener$NativeCrashReporter.run(NativeCrashListener.java:86)
I/WindowState( 522): WIN DEATH: Window{42206ba0 u0 com.DeNA.spineTest/com.unity3d.player.UnityPlayerNativeActivity}
I/WindowState( 522): WIN DEATH: Window{4233cb48 u0 SurfaceView}
I/ActivityManager( 522): Process com.DeNA.spineTest (pid 11650) has died.