Changes the sat switch so it can be disabled

src/nimblepkg/options.nim

@@ -550,7 +550,13 @@ proc parseFlag*(flag, val: string, result: var Options, kind = cmdLongOption) =
       result.developFile = val.normalizedPath
     else:
       raise nimbleError(multipleDevelopFileOptionsGivenMsg)
-  of "sat": result.useSatSolver = true  
+  of "solver": 
+    if val == "sat":
+      result.useSatSolver = true
+    elif val == "legacy":
+      result.useSatSolver = false
+    else:
+      raise nimbleError("Unknown solver option: " & val)
   else: isGlobalFlag = false
 
   var wasFlagHandled = true

tests/tsat.nim

@@ -150,7 +150,7 @@ suite "SAT solver":
           where c has two versions of the same package. The version is retrieved counterintuitively from 
           the nimblemeta.json special version field. 
       ]#
-      let (_, exitCode) = execNimble("install", "-l", "--sat")
+      let (_, exitCode) = execNimble("install", "-l", "--solver:sat")
       check exitCode == QuitSuccess
 
   test "should be able to download a package and select its deps":