build_all.sh fails with error

/Users/xxx/Documents/Bolts-ObjC/Bolts/Common/BFCancellationTokenRegistration.m:32:1: error: cannot synthesize weak property in file using manual reference counting
@implementation BFCancellationTokenRegistration
^
/Users/xxx/Documents/Bolts-ObjC/Bolts/Common/BFCancellationTokenRegistration.m:19:50: note: property declared here
@property (nonatomic, weak) BFCancellationToken *token;
                                                 ^
1 error generated.