Ruby couchbase-1.2.0.z.beta2 fails to install with libcouchbase-2.0.0beta2

gem install couchbase --pre                           
Building native extensions.  
This could take a while...                         
ERROR:  Error installing couchbase:                                             	
ERROR: Failed to build gem native extension.
 
/Users/rg/.rvm/rubies/ruby-1.9.3-p194/bin/ruby extconf.rb
checking for lcb_get() in -lcouchbase... yes
checking for mach/mach_time.h... yes
checking for stdint.h... yes
checking for sys/time.h... yes
checking for clock_gettime()... no
checking for gettimeofday()... yes
checking for QueryPerformanceCounter()... no
creating couchbase_config.h
creating Makefile
 
make
compiling arguments.c
compiling arithmetic.c
arithmetic.c: In function ‘cb_bucket_arithmetic’:
arithmetic.c:97: warning: implicit conversion shortens 64-bit value into a 32-bit value
compiling bucket.c
bucket.c: In function ‘error_callback’:
bucket.c:25: error: ‘struct lcb_io_opt_st’ has no member named ‘stop_event_loop’
bucket.c: In function ‘do_connect’:
bucket.c:269: warning: implicit declaration of function ‘lcb_set_view_complete_callback’
bucket.c:270: warning: implicit declaration of function ‘lcb_set_view_data_callback’
bucket.c:271: warning: implicit declaration of function ‘lcb_set_management_complete_callback’
bucket.c:272: warning: implicit declaration of function ‘lcb_set_management_data_callback’
bucket.c: In function ‘cb_bucket_stop’:
bucket.c:1063: error: ‘struct lcb_io_opt_st’ has no member named ‘stop_event_loop’
make: *** [bucket.o] Error 1
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