build: define nightly tag external to build system

Makefile

@@ -225,8 +225,8 @@ ARCH=x86
 endif
 endif
 TARNAME=node-$(VERSION)
-ifeq ($(NIGHTLY),1)
-TAG = nightly-$(shell date "+%Y%m%d")
+ifdef NIGHTLY
+TAG = nightly-$(NIGHTLY)
 TARNAME=node-$(VERSION)-$(TAG)
 endif
 TARBALL=$(TARNAME).tar.gz
@@ -251,7 +251,7 @@ release-only:
 		echo "" >&2 ; \
 		exit 1 ; \
 	fi
-	@if [ "$(NIGHTLY)" = "1" -o "$(RELEASE)" = "1" ]; then \
+	@if [ "$(NIGHTLY)" != "" -o "$(RELEASE)" = "1" ]; then \
 		exit 0; \
 	else \
 	  echo "" >&2 ; \

vcbuild.bat

@@ -84,10 +84,12 @@ if defined noperfctr set noperfctr_arg=--without-perfctr& set noperfctr_msi_arg=
 @rem Skip project generation if requested.
 if defined noprojgen goto msbuild
 
+if defined NIGHTLY set TAG=nightly-%NIGHTLY%
+
 @rem Generate the VS project.
 SETLOCAL
   if defined VS100COMNTOOLS call "%VS100COMNTOOLS%\VCVarsQueryRegistry.bat"
-  python configure %debug_arg% %nosnapshot_arg% %noetw_arg% %noperfctr_arg% --dest-cpu=%target_arch%
+  python configure %debug_arg% %nosnapshot_arg% %noetw_arg% %noperfctr_arg% --dest-cpu=%target_arch% --tag=%TAG%
   if errorlevel 1 goto create-msvs-files-failed
   if not exist node.sln goto create-msvs-files-failed
   echo Project files generated.
@@ -133,7 +135,7 @@ if not defined msi goto run
 call :getnodeversion
 
 if not defined NIGHTLY goto msibuild
-set NODE_VERSION=%NODE_VERSION%-%date:~10,4%%date:~4,2%%date:~7,2%
+set NODE_VERSION=%NODE_VERSION%.%NIGHTLY%
 
 :msibuild
 echo Building node-%NODE_VERSION%