Use msbuild v14 for linux/darwin.

Benoit Hudson · Benoit Hudson · commit 14bc2e2eb533 · 2018-10-11T13:15:43.000-04:00
Fixes a build break on travis. Seems the latest nuget is finding msbuild 15, whereas pythonnet.sln is for msbuild 14.
diff --git a/setup.py b/setup.py
@@ -329,7 +329,7 @@ def _install_packages(self):
             self.debug_print("Updating NuGet: {0}".format(cmd))
             subprocess.check_call(cmd, shell=use_shell)
 
-            cmd = "{0} restore pythonnet.sln -o packages".format(nuget)
+            cmd = "{0} restore pythonnet.sln  -MSBuildVersion 14 -o packages".format(nuget)
             self.debug_print("Installing packages: {0}".format(cmd))
             subprocess.check_call(cmd, shell=use_shell)
 
