This is interesting... I have the exact opposite problem . It is currently deleting data from my plots even though I have told it to use the data from the last 300 builds...
If you set the plot to store the last 300 data points I want it to display the last 300 data points. I don't care if the build the data is built off of is removed.
I don't want to waste the space storing the build but I do want to keep the plot data as I am trying to view trends over time.
Maybe this should be made an option instead of just doing it one way or the other??
There are also many better ways to handle data that skews the plot (like setting the axis scale) than deleting it. In general terms for my use it is the data that is skewing the plot that I am looking for.