Graph axis for small range has repetitive values

[Matthew Paul Thomas]

When a graph has value labels on an axis, and the graph covers a small range, the labels incorrectly repeat themselves, so you can't tell what the real value is.

Y axis examples:
<https://errors.ubuntu.com/problem/1e4a09ec7376628035e64b1600bef4e3c5b36d93> has Y axis values "0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00"
<https://errors.ubuntu.com/problem/94f7beb32c9a9172de3f9281691510762d655d47> has Y axis values "0.00 0.01 0.01 0.01 0.02 0.03 0.03 0.04 0.04 0.05"

On the X axis, this bug is currently masked by bug 1276178. A previous example (which now 404s) had date labels "09/19/12 09/19/12 09/19/12 09/19/12 09/19/12 09/19/12 09/19/12 09/20/12 09/20/12 09/20/12".

The X axis should never have more tick marks than actual dates, and the Y axis values should be as precise as necessary to be distinct from each other.

Not to be confused with bug 1037612, which is specifically about the first and last labels on an axis.