https://github.com/bitlbee/bitlbee/commit/5c90890fbf5626650b966f23cf141fafa3e4251e
introduces g_hash_table_contains() which is not supported by glib2-2.28.8-10.el6.
https://github.com/EionRobb/skype4pidgin/blob/master/skypeweb/glibcompat.h was the
inspiration for this workaround.

--- bitlbee-3.6/root_commands.c			2019-02-07 20:53:38.000000000 +0100
+++ bitlbee-3.6/root_commands.c.glib2		2019-11-28 21:41:43.853966247 +0100
@@ -29,6 +29,10 @@
 #include "help.h"
 #include "ipc.h"
 
+#if !GLIB_CHECK_VERSION(2, 32, 0)
+#define g_hash_table_contains(hash_table, key) g_hash_table_lookup_extended(hash_table, key, NULL, NULL)
+#endif /* 2.32.0 */
+
 void root_command_string(irc_t *irc, char *command)
 {
 	root_command(irc, split_command_parts(command, 0));
--- bitlbee-3.6/irc_channel.c			2019-02-07 20:53:38.000000000 +0100
+++ bitlbee-3.6/irc_channel.c.glib2		2019-11-28 21:42:12.202142163 +0100
@@ -25,6 +25,10 @@
 
 #include "bitlbee.h"
 
+#if !GLIB_CHECK_VERSION(2, 32, 0)
+#define g_hash_table_contains(hash_table, key) g_hash_table_lookup_extended(hash_table, key, NULL, NULL)
+#endif /* 2.32.0 */
+
 static char *set_eval_channel_type(set_t *set, char *value);
 static gint irc_channel_user_cmp(gconstpointer a_, gconstpointer b_);
 static const struct irc_channel_funcs control_channel_funcs;