add coverage tests, tweak error messages

9 jobs for port-float-symbol-method in 394 minutes and 30 seconds (queued for 56 minutes and 25 seconds)
Status Name Job ID Coverage
  Test
passed debian_stretch_x86_64_deb #17249
x86_64 stretch debian

00:34:39

passed osx_10.11_x86_64_dmg #17233
osx v10.11 dmg

00:37:45

passed osx_10.8_x86_64_dmg #17234
osx v10.8 dmg

00:25:02

passed raspbian_stretch_armv7l_deb #17236
raspbian arm stretch

01:08:42

passed ubuntu_14.04_i386_deb #17230
ubuntu v14.04 i386

00:41:10

passed ubuntu_14.04_x86_64_deb #17231
ubuntu v14.04 x86_64

00:38:37

passed ubuntu_16.04_x86_64_deb #17232
ubuntu v16.04 x86_64

00:39:32

passed windows_i386_innosetup #17235
windows i386

01:48:59

failed debian_stretch_x86_64_deb #17229
debian stretch x86_64