The PGF backend of MPL 1.4.3 causes a "Dimension too large" LaTeX error when processing a log-scale plot with a point at zero. The error is

[...]
! Dimension too large.
<to be read again> 
                   \pgf@y 
l.69 ...\pgfqpoint{-2148537.332542in}{0.600000in}}
                                                  %
No pages of output.
Transcript written on figure.log.

Obviously, the x coordinate of the point is way out of bounds. The script triggering the error is

import matplotlib as mpl
mpl.use('pgf')
import matplotlib.pyplot as plt

fig, ax = plt.subplots()
ax.plot([0, 1], [.5, 1])
ax.set_xscale('log')
fig.savefig('fig.pdf')

Adding nonposx='mask' to the call to set_xscale prevents the error but produces a plot consisting of only a single point. The PGF version installed is 2.10 but the error also occurs with PGF 3.00.