write conflicts not detected because of dirty tracking and race condition

[langalex]

• one process loads a document
• another process loads the same document
• the first process changes and saves the doc
• the 2nd process makes a change that leads to dirty tracking not detecting a change
• the 2nd process does not actyually save the doc and hence detects no write conflict

process 1:

d = db.load '1'
d.some_value # 'bar'
db.save d do |dd|
  dd.some_value = 'foo'
end

process 2:

d = db.load '1'
d.some_value # 'bar'
db.save d do |dd| # does not save because d.some_value == 'bar', even though by now d.some_value == 'foo'
  dd.some_value = 'bar'
end