Fix warnings when rebalancing FIDs on busy network

When you have rebalance working across a busy network, then the size check of
all the copies of the fid can fail, causing a warning to be issued.

(Tomas Doran)

git-svn-id: http://code.sixapart.com/svn/mogilefs/trunk@1421 f67b2e87-0811-0410-a7e0-dd94e48410d6

lib/MogileFS/DevFID.pm

@@ -73,6 +73,8 @@ sub size_matches {
     my $fid = $self->fid;
     my $disk_size = $self->size_on_disk;
 
+    # Temporary connectivity error with that disk/machine..
+    return 0 unless defined $disk_size;
     return 0 if $disk_size == MogileFS::HTTPFile::FILE_MISSING;
 
     return $disk_size == $fid->length;