The status of the bug is labeled as Won't fix and I can understand why in this context.

The right way would have been to run ALTER TABLE tbl_name DROP PARTITION; because the MySQL Documentation on ALTER TABLE Partition Operations says:

DROP PARTITION can be used to drop one or more RANGE or LIST partitions. This statement cannot be used with HASH or KEY partitions; instead, use COALESCE PARTITION (see below). Any data that was stored in the dropped partitions named in the partition_names list is discarded.

ALTER TABLE t1 DROP PARTITION p0, p1;

Once you ran ALTER TABLE tbl_name DISCARD TABLESPACE;, the data dictionary should no longer be aware of the physical presence of the orphaned .ibd files. However, since the bug does not reclaim the diskspace, perhaps the data dictionary entries for your tables is intact. Let's find out.

WARNING : You should run service mysql stop and do a physical backup of /var/lib/mysql

First do this: SHOW CREATE TABLE tbl_name\G

Then, run SELECT * FROM tbl_name WHERE (stuff from partition #x) LIMIT 10;

to test the table's usability of each partition.

Once you are confortable with the table usability, you can any of the following:

REMOVE ANY PARTITION YOU WANT

ALTER TABLE tbl_name DROP PARTITION partition-name;

If you do not trust ALTER TABLE tbl_name DROP PARTITION partition-name;, do it manually

CREATE TABLE tbl_name2 LIKE tbl_name;
ALTER TABLE tbl_name2 DROP PARTITION partition-name;
INSERT INTO tbl_name2 SELECT * FROM tbl_name WHERE (anything but stuff from partition-name)
ALTER TABLE tbl_name RENAME tbl_name9;
ALTER TABLE tbl_name2 RENAME tbl_name;
DROP TABLE tbl_name9;   

DROP ALL DATA FROM PARTITION BUT KEEP PARTITION

ALTER TABLE tbl_name TRUNCATE PARTITION partition-name;

If you do not trust ALTER TABLE tbl_name TRUNCATE PARTITION partition-name;, do it manually

CREATE TABLE tbl_name2 LIKE tbl_name;
INSERT INTO tbl_name2 SELECT * FROM tbl_name WHERE (anything but stuff from partition-name)
ALTER TABLE tbl_name RENAME tbl_name9;
ALTER TABLE tbl_name2 RENAME tbl_name;
DROP TABLE tbl_name9;   

CREATE A BLANK TABLE

CREATE TABLE tbl_name2 LIKE tbl_name;
DROP TABLE tbl_name;
ALTER TABLE tbl_name2 RENAME tbl_name;

Give it a Try !!!

UPDATE 2013-05-20 18:41 EDT

I am glad you were able to drop the partition.

I have some distressing news: It is not possible to shrink ibdata1 without dumping all the data, deleting ibdata1, restarting mysql, and reloading.

Here are my past posts on how to do that safely:

• May 21, 2012 : How large will a MySQL database be relative to the dump file?
• Apr 01, 2012 : Is innodb_file_per_table advisable?
• Mar 25, 2012 : Why does InnoDB store all databases in one file?
• Feb 04, 2011 : MySQL InnoDB - innodb_file_per_table cons?
• Oct 29, 2010 : Howto: Clean a mysql InnoDB storage engine?

On one hand, you can have a look at one of my previous answers to see how you can keep a table size more or less steady. There you will find a solution with triggers - of course, this can be solved using a cron job as well. In the latter case I would first check if the row number exceeded a certain limit and the either delete the oldest rows or drop a partition.

On the other hand, as you already noticed, one has to take care of the disk space where pg_xlog is. When it gets full, it is not that easy to recover... But checking your database settings you can have a fair estimation how much space you need:

There will always be at least one WAL segment file, and will normally not be more than (2 + checkpoint_completion_target) * checkpoint_segments + 1 or checkpoint_segments + wal_keep_segments + 1 files. Each segment file is normally 16 MB (though this size can be altered when building the server). You can use this to estimate space requirements for WAL. Ordinarily, when old log segment files are no longer needed, they are recycled (renamed to become the next segments in the numbered sequence). If, due to a short-term peak of log output rate, there are more than 3 * checkpoint_segments + 1 segment files, the unneeded segment files will be deleted instead of recycled until the system gets back under this limit.

If you don't have replication set up, the maximum is 3 * checkpoint_segments + 1 (times 16 MB). A typical replicationless setup will need something under 10 GB for pg_xlog, I think.