System.Text.RegularExpressions 4.3.1 was recently added in dotnet/source-build-assets#332. It looks like not all of the dependent packages were included. A partial walk of the dependency tree shows the following packages are required:
System.Runtime.Extensions, 4.3.1
Microsoft.NETCore.Targets, 1.1.3
In addition to these missing packages, the project ordering mechanism must be used to specify the build order since these are new packages. See dotnet/source-build-assets@49e322b#diff-366b25472963c6b33188d84139f6c8997298c5adc857a2624ab0d26a2d87baf0R4 for details.
System.Text.RegularExpressions 4.3.1 was recently added in dotnet/source-build-assets#332. It looks like not all of the dependent packages were included. A partial walk of the dependency tree shows the following packages are required:
System.Runtime.Extensions, 4.3.1
Microsoft.NETCore.Targets, 1.1.3
In addition to these missing packages, the project ordering mechanism must be used to specify the build order since these are new packages. See dotnet/source-build-assets@49e322b#diff-366b25472963c6b33188d84139f6c8997298c5adc857a2624ab0d26a2d87baf0R4 for details.