nim-1.6 series compilers give pretty odd error:

  bu/dirq.nim(77, 16) Error: undeclared identifier: 'parseOnly'
(odd since this is a keyword argument..).

Since nim-2.2 is imminent, rather than try to track that down (it
may be fix in 1.6-latest for all I know), update minimum version
in nimble to 2.0.0.  Compiles fine for me on nim-2.0.8, anyway.

bu.nimble

@@ -158,5 +158,5 @@ else:
  ]
 
 # Dependencies
-requires "nim >= 1.6.0", "cligen >= 1.7.2",
+requires "nim >= 2.0.0", "cligen >= 1.7.2",
          "adix >= 0.6.0", "nio >= 0.7.1", "fitl >= 0.5.7", "spfun >= 0.7.0"