Merge lp:~percona-toolkit-dev/percona-toolkit/change-diskstats-group-by-default-fix-bug-952727 into lp:percona-toolkit/2.1

[Baron Schwartz]

[Baron Schwartz (baron-xaprb)]

I've run all the tests and they pass.

[Daniel Nichter (daniel-nichter)]

review: Approve

=== modified file 'bin/pt-diskstats'
--- bin/pt-diskstats	2012-03-07 23:41:54 +0000
+++ bin/pt-diskstats	2012-03-30 15:32:24 +0000
@@ -3938,12 +3938,13 @@
 
 =item --group-by
 
-type: string; default: disk
+type: string; default: all
 
-Group-by mode: disk, sample, or all.  In B<disk> mode, each line of output shows
-one disk device.  In B<sample> mode, each line of output shows one sample of
-statistics.  In B<all> mode, each line of output shows one sample and one disk
-device.
+Group-by mode: disk, sample, or all.  In B<disk> mode, each line of output
+shows one disk device, with the statistics computed since the tool started.  In
+B<sample> mode, each line of output shows one sample of statistics, with all
+disks averaged together.  In B<all> mode, each line of output shows one sample
+and one disk device.
 
 =item --headers
 
 
=== modified file 't/pt-query-digest/mirror.t'
--- t/pt-query-digest/mirror.t	2012-03-06 20:23:20 +0000
+++ t/pt-query-digest/mirror.t	2012-03-30 15:32:24 +0000
@@ -36,6 +36,9 @@
 my $pid_file = "/tmp/pt-query-digest-mirror-test.pid";
 diag(`rm $pid_file 2>/dev/null`);
 
+my $pid_file = '/tmp/pt-query-digest.test.pid';
+`rm -rf $pid_file >/dev/null`;
+
 # ##########################################################################
 # Tests for swapping --processlist and --execute
 # ##########################################################################