vcs.rb: fix for baseruby 2.2

tool/lib/vcs.rb

@@ -599,7 +599,8 @@ class VCS
                   s[$2.to_i, 0] = "#{$1}#{$3}\n"
                 when %r[^ +(\d+)(?:,(\d+))?d]
                   n = $1.to_i
-                  s[n..($2&.to_i || n)] = []
+                  e = $2
+                  s[n..(e ? e.to_i : n)] = []
                 end
               end
               s = s.join('')