auto merge of #17538 : brson/rust/winmk, r=alexcrichton

Author: bors

configure

@@ -488,7 +488,7 @@ esac
 
 # Continue supporting the old --enable-nightly flag to transition the bots
 # XXX Remove me
-if [ $CFG_ENABLE_NIGHTLY -eq 1 ]
+if [ ! -z "$CFG_ENABLE_NIGHTLY" ]
 then
     CFG_RELEASE_CHANNEL=nightly
     putvar CFG_RELEASE_CHANNEL

mk/stage0.mk

@@ -3,8 +3,11 @@
 $(HBIN0_H_$(CFG_BUILD))/:
 	mkdir -p $@
 
+# On windows these two are the same, so cause a redifinition warning
+ifneq ($(HBIN0_H_$(CFG_BUILD)),$(HLIB0_H_$(CFG_BUILD)))
 $(HLIB0_H_$(CFG_BUILD))/:
 	mkdir -p $@
+endif
 
 $(SNAPSHOT_RUSTC_POST_CLEANUP): \
 		$(S)src/snapshots.txt \