symbol binding on dlopen

[Sean McNeil]

I have been trying to formulate a reasonable explanation why I am seeing
the following behavior:

1) start bash with nss_ldap.
2) nss_ldap pulls in libpthread.so.1 via. some non-direct dependency -
libdb41.so.1.
3) Constructor is called for libpthread.so.1 that installs signal
handler wrappers.
4) libreadline.so.4 uses sigaction, but it is not binding to the strong
symbol of libpthread.so.1.  It is still using the older one.

Is this expected?  Symbols will only be bound on the immediate
dependencies of what is loaded by dlopen, or should all symbols within
the closure be bound?

Sean