Pidgin 2.x.y does not compile

[Bjoern Voigt]

Since some weeks I can not compile Pidgin (release-2.x.y branch)
because of an inconsistency in Oscar plugin:

$ make
[...]
make[5]: Entering directory
'/home/user/pidgin-hg-2.x.y/libpurple/protocols/oscar'
  CC       liboscar_la-oscar.lo
oscar.c: In function 'flap_connection_established':
oscar.c:551:6: error: 'FlapConnection' has no member named 'conn'
  conn->conn = TRUE;
      ^
[...]

oscar.c:551:
static int
flap_connection_established(OscarData *od, FlapConnection *conn,
FlapFrame *fr, ...)
{
    conn->conn = TRUE;
[...]

FlapConnection (defined in libpurple/protocols/oscar/oscar.h) really
has no member "conn".

Greetings,
Björn