mkdir $WORK/out
txtar-addmod $WORK/out github.com/shurcooL/httpfs@v0.0.0-20171119174359-809beceb2371
! stdout .+
! stderr .+
exists $WORK/out/github.com_shurcoo!l_httpfs_v0.0.0-20171119174359-809beceb2371.txt