This metaphor almost certainly refers to the practice of establishing the first conditional check in a `while` loop.  If you don't do this, *the loop won't work.*  It is a well-established pattern, and it hasn't changed since the `while` loop was invented.  The requirement for setting the initial condition in a `while` loop is *not a defect.*

<!-- language-all: c# -->

	int i = 0; // prime the pump
	while (i < 10)
	{
		Console.Write("While statement ");
		Console.WriteLine(i);
		i++; // set condition again
	}

The primer can be a read statement, or whatever properly sets the initial condition.  Setting the initial condition using a read statement is called a "Priming Read."

	string line;

	using (StreamReader file = new StreamReader("c:\\test.txt"))
	{
		line = file.ReadLine(); // Priming read.
		while(line != null)
		{
			Console.WriteLine (line);
			line = file.ReadLine(); // Subsequent reads.   
		}
	}

In C#, the two `Readline()` calls can be combined into a single statement within the conditional:

	while ((line = r.ReadLine()) != null)
	{
		Console.WriteLine (line);
	}