status: use unpaired ver constr when checking updateability

This changes fixes a bug due to which the LATEST field in status was
missing for projects that were not in manifest but in lock and had
pairedVersion.

Since we check `bs.Version` to not be nil before entering into
updateability block, we can use the same value as the constraint for
matching with the version list obtained for the projects.

cmd/dep/status.go

@@ -551,7 +551,8 @@ func runStatusAll(ctx *dep.Ctx, out outputter, p *dep.Project, sm gps.SourceMana
 						// Get constraint for locked project
 						for _, lockedP := range p.Lock.P {
 							if lockedP.Ident().ProjectRoot == proj.Ident().ProjectRoot {
-								c.Constraint = lockedP.Version()
+								// Use the unpaired version as the constraint for checking updates.
+								c.Constraint = bs.Version
 							}
 						}
 					}