Is the line style supposed to depend on the export backend?

MPL 1.5.1 is from Anaconda and MPL 2.x is from Github, both on Linux (CentOS 7)

With MPL 1.5.1, I get the same line styles between both PDF and PNG exports:

• PNG @ 100 DPI:

• PDF @ None DPI:MPL_ver_1.5.1_None.pdf

while with master version, they are different between PDF and PNG exports:

• PNG @ 100 DPI:

• PDF @ None DPI:MPL_ver_2.0.0b1.post1628+g1aba7c3_None.pdf

NB: the problem seems to be independent from the DPI value: I get similar line styles between both PNG exports with 100 DPI and 300 DPI.

• PNG @ 300 DPI:

The example snippet is

importmatplotlibimportmatplotlib.pyplotaspltimportnumpyasnptest_case=matplotlib.__version__fig,ax=plt.subplots(num=test_case,figsize=(4.8,3.2))ax.set_title("MPL version: {0:s}".format(test_case))xx=np.array([0.0,1.0])ax.plot(xx,1*xx,ls='dashed',label='default lw')ax.plot(xx,2*xx,ls='dashed',lw=2,label='lw=2')ax.plot(xx,3*xx,ls='dashed',lw=3,label='lw=3')ax.legend(loc='upper left')plt.show()forext,dpiin (('pdf',None), ('png',100), ('png',300)):fig.savefig("MPL_ver_{v:s}_{d}.{e:s}".format(v=test_case,d=dpi,e=ext),dpi=dpi)

My guess would that I may be somehow related to the new behavior introduced in#5926,but I didn't have time to have a look yet.