No, do not abort. You need the complete Cyanogenmod source not only the Nexus specific device bits.
<project path="device/lge/hammerhead" name="RealJohnGalt/android_device_lge_hammerhead" revision="cm-12.1" /> <project path="kernel/lge/hammerhead" name="RealJohnGalt/android_kernel_lge_hammerhead" revision="cm-12.1" />
Checking out files: 100% (195/195), done. Syncing work tree: 100% (172/172), done.
#### make completed successfully (03:10 (mm:ss)) ####