dtruss -f is not following children processes?

Following is not following the child "sql.py" python process:

sudo dtruss -f run-test sql.py 2>&1

Here is the output - which shows no evidence of following the invoked python:

PID/THRD SYSCALL(args) = return 1948/0x7177: execve("/Library/Java/JavaVirtualMachines/jdk1.7.0_25.jdk/Contents/Home/bin/bash\0", 0x7FFF50B43B18, 0x7FFF50B43B38) = -1 Err#2 1948/0x7177: execve("/usr/local/mysql/bin/bash\0", 0x7FFF50B43B18, 0x7FFF50B43B38) = -1 Err#2 1948/0x7177: execve("/shared/bin/bash\0", 0x7FFF50B43B18, 0x7FFF50B43B38) = -1 Err#2 1948/0x7177: execve("/shared/maven3/bin/bash\0", 0x7FFF50B43B18, 0x7FFF50B43B38) = -1 Err#2 1948/0x7177: execve("/shared/jruby/bin/bash\0", 0x7FFF50B43B18, 0x7FFF50B43B38) = -1 Err#2 1948/0x7177: execve("/shared/scala/bin/bash\0", 0x7FFF50B43B18, 0x7FFF50B43B38) = -1 Err#2 1948/0x7177: execve("/usr/local/Cellar/hadoop/1.2.1/bin/bash\0", 0x7FFF50B43B18, 0x7FFF50B43B38) = -1 Err#2 1948/0x7177: execve("/usr/local/Cellar/hadoop/1.2.1/sbin/bash\0", 0x7FFF50B43B18, 0x7FFF50B43B38) = -1 Err#2 1948/0x7177: execve("/shared/hbase-0.98.8-hadoop2/bin/bash\0", 0x7FFF50B43B18, 0x7FFF50B43B38) = -1 Err#2 1948/0x7177: execve("/shared/ruby-1.8.7/bin/bash\0", 0x7FFF50B43B18, 0x7FFF50B43B38) = -1 Err#2 1948/0x7177: execve("/shared/bash\0", 0x7FFF50B43B18, 0x7FFF50B43B38) = -1 Err#2 1948/0x7177: execve("./bash\0", 0x7FFF50B43B18, 0x7FFF50B43B38) = -1 Err#2 1948/0x7177: execve("/sbin/bash\0", 0x7FFF50B43B18, 0x7FFF50B43B38)

= -1 Err#2 1948/0x7177: execve("/usr/sbin/bash\0", 0x7FFF50B43B18, 0x7FFF50B43B38) = -1 Err#2 1948/0x7177: execve("/usr/bin/bash\0", 0x7FFF50B43B18, 0x7FFF50B43B38) = -1 Err#2 1948/0x7177: execve("/usr/local/bin/bash\0", 0x7FFF50B43B18, 0x7FFF50B43B38) = -1 Err#2 1948/0x7177: thread_selfid(0x0, 0x0, 0x0) = 29047 0 1948/0x7177: csops(0x0, 0x0, 0x7FFF50B43198) = 0 0 1948/0x7177: issetugid(0x0, 0x0, 0x7FFF50B43198) = 0 0 1948/0x7177: shared_region_check_np(0x7FFF50B410D8, 0x0, 0x7FFF50B43198) = 0 0 1948/0x7177: stat64("/usr/lib/dtrace/libdtrace_dyld.dylib\0", 0x7FFF50B42268, 0x7FFF50B43198) = 0 0 1948/0x7177: open("/usr/lib/dtrace/libdtrace_dyld.dylib\0", 0x0, 0x0) = 3 0 1948/0x7177: pread(0x3, "\312\376\272\276\0", 0x1000, 0x0) = 4096 0 1948/0x7177: pread(0x3, "\317\372\355\376\a\0", 0x1000, 0x1000) = 4096 0 1948/0x7177: fcntl(0x3, 0x3D, 0x7FFF50B405D0) = 0 0 1948/0x7177: mmap(0x10F0C6000, 0x2000, 0x5, 0x12, 0x3, 0x1000) = 0x10F0C6000 0 1948/0x7177: mmap(0x10F0C8000, 0x1000, 0x3, 0x12, 0x3, 0x3000) = 0x10F0C8000 0 1948/0x7177: mmap(0x10F0C9000, 0x1FC0, 0x1, 0x12, 0x3, 0x4000) = 0x10F0C9000 0 1948/0x7177: close(0x3)

= 0 0 1948/0x7177: stat64("/usr/lib/dtrace/libdtrace_dyld.dylib\0", 0x7FFF50B42BE8, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/libSystem.B.dylib\0", 0x7FFF50B42098, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/libcache.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/libcommonCrypto.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/libcompiler_rt.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/libcopyfile.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/libcorecrypto.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/libdispatch.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/libdyld.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/libkeymgr.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/liblaunch.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/libmacho.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/libquarantine.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/libremovefile.dylib\0", 0x7FFF50B41C88, 0x1)

= 0 0 1948/0x7177: stat64("/usr/lib/system/libsystem_asl.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/libsystem_blocks.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/libsystem_c.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/libsystem_configuration.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/libsystem_coreservices.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/libsystem_coretls.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/libsystem_dnssd.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/libsystem_info.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/libsystem_kernel.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/libsystem_m.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/libsystem_malloc.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/libsystem_network.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/libsystem_networkextension.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/libsystem_notify.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/libsystem_platform.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/libsystem_pthread.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/libsystem_sandbox.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/libsystem_secinit.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/libsystem_stats.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/libsystem_trace.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/libunc.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/libunwind.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/system/libxpc.dylib\0", 0x7FFF50B41C88, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/libobjc.A.dylib\0", 0x7FFF50B40F68, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/libauto.dylib\0", 0x7FFF50B40F68, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/libc++abi.dylib\0", 0x7FFF50B40E48, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/libc++.1.dylib\0", 0x7FFF50B40E48, 0x1) = 0 0 1948/0x7177: stat64("/usr/lib/libDiagnosticMessagesClient.dylib\0", 0x7FFF50B40D38, 0x1) = 0 0 1948/0x7177: getpid(0x7FFF8D995740, 0x7FFF50B40D38, 0x1) = 1948 0 1948/0x7177: sysctl(0x7FFF50B426D8, 0x2, 0x7FFF50B426E8) = 0 0 1948/0x7177: thread_selfid(0x7FFF50B426D8, 0x2, 0x7FFF50B426E8) = 29047 0 1948/0x7177: bsdthread_register(0x7FFF92FD84A4, 0x7FFF92FD8494, 0x2000) = 1073741855 0 1948/0x7177: mprotect(0x10F0C2000, 0x88, 0x1) = 0 0 1948/0x7177: mprotect(0x10F0CB000, 0x1000, 0x0) = 0 0 1948/0x7177: mprotect(0x10F0E1000, 0x1000, 0x0) = 0 0 1948/0x7177: mprotect(0x10F0E2000, 0x1000, 0x0) = 0 0 1948/0x7177: mprotect(0x10F0F8000, 0x1000, 0x0) = 0 0 1948/0x7177: mprotect(0x10F0C4000, 0x1000, 0x1) = 0 0 1948/0x7177: mprotect(0x10F0C2000, 0x88, 0x3) = 0 0 1948/0x7177: mprotect(0x10F0C2000, 0x88, 0x1) = 0 0 1948/0x7177: issetugid(0x10F0C2000, 0x88, 0x1) = 0 0 1948/0x7177: getpid(0x10F0C2000, 0x88, 0x1) = 1948 0 1948/0x7177: stat64("/AppleInternal/XBS/.isChrooted\0", 0x7FFF50B42638, 0x1) = -1 Err#2 1948/0x7177: stat64("/BuildSupport/makeProject\0", 0x7FFF50B42638, 0x1) = -1 Err#2 1948/0x7177: stat64("/AppleInternal\0", 0x7FFF50B425A8, 0x1) = -1 Err#2 1948/0x7177: csops(0x79C, 0x7, 0x7FFF50B420D0) = 0 0 1948/0x7177: csops(0x79C, 0x7, 0x7FFF50B419B0) = 0 0 1948/0x7177: open("/dev/dtracehelper\0", 0x2, 0x7FFF50B43090) = 3 0 1948/0x7177: ioctl(0x3, 0x80086804, 0x7FFF50B43018) = 0 0 1948/0x7177: close(0x3) = 0 0