Plot does not show unless 0 meridian is included in extent

Description

For data which is here: http://www.sharecsv.com/s/76dd767525a37180ca54cd1d9314b9dc/t1.csv, the plot doesn't appear unless 0 is included in extent. I have described my experiments here too: https://stackoverflow.com/questions/57585433/facing-weird-problem-when-trying-to-plot-simple-lat-lon-points

Code to reproduce

This does not work:

    test_ax = plt.axes(projection=ccrs.Mercator())
    test_ax.plot(test_df['lon'], test_df['lat'], color="blue", linewidth=4, alpha=1.0, transform=ccrs.Geodetic())
    test_ax.coastlines()
    test_ax.gridlines(draw_labels=True)
    plt.show()

This code shows the plot (the blue dot near San Francisco)

    test_ax = plt.axes(projection=ccrs.Mercator())
    test_ax.plot(test_df['lon'], test_df['lat'], color="blue", linewidth=4, alpha=1.0, transform=ccrs.Geodetic())
    test_ax.coastlines()
    test_ax.set_extent([-130, 0, 30, 40], crs=ccrs.Geodetic())
    test_ax.gridlines(draw_labels=True)
    plt.show()

Edit - 2

(Edit-1 contains a reproducible example. I am adding a simplified reproducible example here).

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
import cartopy.crs as ccrs

test_df = pd.DataFrame()
test_df['lon'] = np.linspace(-120, -60, num=1000)
test_df['lat'] = 38

fig = plt.figure()

test_ax = fig.add_axes((0, 0, 1, 0.3), projection=ccrs.Mercator())
test_ax.plot(test_df['lon'], test_df['lat'], color="blue", linewidth=4, alpha=1.0, transform=ccrs.Geodetic())
test_ax.coastlines()
gl = test_ax.gridlines(draw_labels=True)
gl.xlabels_top = False
gl.ylabels_left = False
test_ax.set_title('Path shows with {} points'.format(len(test_df)))

test_df = pd.DataFrame()
test_df['lon'] = np.linspace(-120, -60, num=1001)
test_df['lat'] = 38
test_ax1 = fig.add_axes((0, 0.3, 1, 0.3), projection=ccrs.Mercator())
test_ax1.plot(test_df['lon'], test_df['lat'], color="blue", linewidth=4, alpha=1.0, transform=ccrs.Geodetic())
test_ax1.coastlines()
gl = test_ax1.gridlines(draw_labels=True)
gl.xlabels_top = False
gl.ylabels_left = False
test_ax1.set_title('Path does not show with {} points'.format(len(test_df)))

test_ax2 = fig.add_axes((0, 0.6, 1, 0.4), projection=ccrs.Mercator())
test_ax2.plot(test_df['lon'], test_df['lat'], color="blue", linewidth=4, alpha=1.0, transform=ccrs.Geodetic())
test_ax2.coastlines()
test_ax2.set_extent((-120, 0, 36, 38))
gl = test_ax2.gridlines(draw_labels=True)
gl.xlabels_top = False
gl.ylabels_left = False
test_ax2.set_title('Path shows with {} points with 0 lon included in extent'.format(len(test_df)))

plt.show()

Edit - 1

I am adding a reproducible example (for jupyter notebook)

import matplotlib.pyplot as plt
import cartopy.crs as ccrs
import pandas as pd

df_csv_url = 'http://www.sharecsv.com/dl/76dd767525a37180ca54cd1d9314b9dc/t1.csv'
test_df = pd.read_csv(df_csv_url)
figure_params = { 'width': 9.6, 'height': 5.4 }

fig = plt.figure(
        figsize=(figure_params["width"], figure_params["height"])        
    )
test_ax = fig.add_axes((0, 0.5, 0.5, 0.5), projection=ccrs.Mercator(), label="map1")
test_ax.plot(test_df['lon'], test_df['lat'], color="blue", linewidth=4, alpha=1.0, transform=ccrs.Geodetic())
test_ax.coastlines()
test_ax.gridlines(draw_labels=True)
test_ax.set_title("Path doesn\'t show", y=1.5)

# Including 0 meridian in extent shows the path
test_ax1 = fig.add_axes((0, 0, 0.5, 0.5), projection=ccrs.Mercator(), label="map2")
test_ax1.plot(test_df['lon'], test_df['lat'], color="blue", linewidth=4, alpha=1.0, transform=ccrs.Geodetic())
test_ax1.set_extent([-130, 0, 30, 40], crs=ccrs.Geodetic())
test_ax1.coastlines()
test_ax1.gridlines(draw_labels=True)
test_ax1.set_title("Path shows (blue dot near San Francisco)", y=1.1)

plt.show()

index

Full environment definition

### Operating system Ubuntu 18.04.3 LTS ### Cartopy version Cartopy==0.17.0 ### conda list NA ### pip list ``` Package Version ------------------ ----------- appdirs 1.4.3 argh 0.26.2 arrow 0.10.0 atomicwrites 1.3.0 attrs 19.1.0 backcall 0.1.0 beautifulsoup4 4.7.1 black 19.3b0 bleach 3.1.0 Cartopy 0.17.0 certifi 2019.3.9 chardet 3.0.4 Click 7.0 click-plugins 1.1.1 cligj 0.5.0 colorama 0.4.1 cycler 0.10.0 decorator 4.1.2 defusedxml 0.6.0 docopt 0.6.2 entrypoints 0.3 Fiona 1.8.6 idna 2.8 importlib-metadata 0.18 ipdb 0.10.3 ipykernel 5.1.1 ipython 6.2.1 ipython-genutils 0.2.0 ipywidgets 7.4.2 jedi 0.11.0 Jinja2 2.10.1 jsonschema 3.0.1 jupyter 1.0.0 jupyter-client 5.2.4 jupyter-console 6.0.0 jupyter-core 4.4.0 kiwisolver 1.1.0 lxml 4.3.3 MarkupSafe 1.1.1 matplotlib 3.1.0 mistune 0.8.4 more-itertools 7.0.0 munch 2.3.2 nbconvert 5.5.0 nbformat 4.4.0 notebook 5.7.8 numpy 1.16.3 olefile 0.44 packaging 19.0 pandas 0.24.2 pandocfilters 1.4.2 parso 0.1.0 pathtools 0.1.2 pendulum 2.0.5 pexpect 4.2.1 pickleshare 0.7.4 Pillow 4.3.0 pip 19.1.1 pluggy 0.12.0 prometheus-client 0.6.0 prompt-toolkit 1.0.15 ptyprocess 0.5.2 py 1.8.0 pygdal 2.2.3.5 Pygments 2.2.0 pyparsing 2.4.0 pyrsistent 0.15.2 pyshp 2.1.0 pytest 4.6.3 pytest-watch 4.2.0 python-dateutil 2.6.1 pytz 2019.1 pytzdata 2019.2 PyYAML 5.1.1 pyzmq 18.0.1 qtconsole 4.4.4 requests 2.22.0 scipy 1.3.0 Send2Trash 1.5.0 setuptools 41.0.1 Shapely 1.6.4.post2 simplegeneric 0.8.1 simplekml 1.3.1 six 1.11.0 soupsieve 1.9.1 sox 1.3.0 termcolor 1.1.0 terminado 0.8.2 testpath 0.4.2 toml 0.10.0 tornado 6.0.2 traitlets 4.3.2 urllib3 1.25.3 watchdog 0.9.0 wcwidth 0.1.7 webencodings 0.5.1 wheel 0.33.4 widgetsnbextension 3.4.2 zipp 0.5.1 ```

SciTools / cartopy