[error][/usr/local/share/perl5/MHA/ManagerUtil.pm, ln178] Got ERROR: Use of uninitialized value $msg in scalar chomp at /usr/local/share/perl5/MHA/ManagerConst.pm line 90

以下で解決できました

vi /usr/local/share/perl5/MHA/ManagerConst.pm

     87 our $log_fmt = sub {
     88   my %args = @_;
     89   my $msg  = $args{message};
     90   $msg = "" unless($msg);　⇒　ここが追加された
     91   chomp $msg;
     92   if ( $args{level} eq "error" ) {
     93     my ( $ln, $script ) = ( caller(4) )[ 2, 1 ];
     94     $script =~ s/.*:://;
     95     return sprintf( "[%s][%s, ln%d] %s\n", $args{level}, $script, $ln, $msg );
     96   }
     97   return sprintf( "[%s] %s\n", $args{level}, $msg );
     98 };

http://code.google.com/p/mysql-master-ha/issues/detail?id=29

お試しあれー