Incorrect dependency caching

[rdnt]

Consider the following example:

build:
  one:
    input: file1
    cmd: touch file2
    target: file2
  two:
    dependsOn:
      - one
    input: *
    cmd: touch file4
    target: file4

• We run bob build two (both tasks are re-built)
• If we then modify file1, and run bob build one, the task is properly re-built.
• If we now run bob build two, it will show as cached, even if the target of one has changed.