If you remove the re-generated image, does it pass? (I can't spot the differences in the github UI)

          ImageComparisonFailure: images not close (RMS 0.044):
          	result_images/test_axes/log_scales_svg.png
          	result_images/test_axes/log_scales-expected_svg.png

It seems to be the svg image (not the png one, which I updated) which is failing.

It's not failing locally on my OSX machine, and isn't failing on the OSX build either, so there must be a difference between linux and OSX when it comes to svg.

@dstansby maybe you need regenerate the SVG too.

It's not failing on my machine, so I have no way to regenerate it! I presume if a linux box regenerated it the OSX build would fail?

(note to myself to restart travis when #8672 gets merged)

@dstansby done for you.

Restarting travis didn't move the build to 14.04, so manually cycling the PR.

Huh, still no luck on travis, will try and see what happens on a local linux box at some point.

Can you check the history of why this was changed to clip? I have a vague memory that there was a long discussion at the time...

It was originally changed to fix #163 (comment) - changing it back will break that problem, so I adding the code in that comment as a test would be a good idea.

I do not see what changed about the test image...

I think the basic idea of this--essentially reverting #2147 and thereby restoring problematic errorbar behavior (#163)--will have to be noted, and we will have to be prepared for someone to raise the issue again. Overall I think it is an improvement, though.

I think that the errorbar problem could be fixed in the errorbar code in this way: for any errorbar covering a range from negative to positive values, insert a point in the Line2D at 1e-300. It would have no effect with a linear scale, and with a log scale it would allow a line to be plotted after the negative end-point is masked out. Worth the trouble? I'm not sure.

I am in favor of:

• reverting Make nonposy='clip' default for log scale y-axes #2147 (with an API changes documentation)
• adding a note to the errorbar docstring that, by default, errorbars which go negative will be clipped on log scales