Below is a list of the bugs that are fixed by patch 2 for Tcl 7.4
(Tcl 7.4p2):

8/4/95 (bug fix) C-level trace callbacks for variables were sometimes
receiving the PART1_NOT_PARSED flag, which could cause errors in
subsequent Tcl library calls using the flags.

8/4/95 (bug fix) Calls to toupper and tolower weren't using the
UCHAR macros, which caused trouble in non-U.S. locales. (JO)

8/25/95 (bug fix) Undid change from 7/19, so that commands can stay
around while their deletion callbacks execute.  Added lots of code to
handle all of the reentrancy problems that this opens up.

8/28/95 (bug fix) Exec wasn't handling bad user names properly, as
in "exec ~bogus_user/foo".