Add integration test for map reassignment

Makefile

@@ -17,13 +17,12 @@ endif
 ifeq (1,$(REDOX))
 	undefine ARGSV
 	ARGS += --target x86_64-unknown-redox
-	PREARGS += +nightly
 endif
 
 .PHONY: all clean distclean install uninstall
 
 all: version extract .cargo/config
-	cargo $(PREARGS) build $(ARGS) $(ARGSV)
+	cargo build $(ARGS) $(ARGSV)
 
 clean:
 	cargo clean

examples/maps.ion

@@ -23,3 +23,8 @@ echo @map[key3]
 
 let map:bmap[float] = [ichi=1.0 ni=2.0 san=3.0]
 echo @map
+
+let map[ichi] = foo
+echo @map
+let map[ni] = bar
+echo @map

examples/maps.out

@@ -12,3 +12,5 @@ one
 two
 three
 ichi 1.0 ni 2.0 san 3.0
+ichi foo ni 2.0 san 3.0
+ichi foo ni bar san 3.0