BUG [rebuild] nim doesn't rebuild when it should

[timotheecour]

• if we change dir and --lib:lib points to a new Nim location
  nim c -r --lib:lib main
  cd other_nim
  nim c -r --lib:lib main
  should rebuild but doesn't

analog to nim-lang#12933

• in this strange case:

cd $vitanim_D
nim c -r testcases/t10334.nim
nim c -r testcases/t10334.nim # doesn't rebuild, runs wrong binary

=> doesn't rebuild when the binary itself runs the same file eg via:

execShellCmd "{getCurrentCompilerExe()} c -r -d:foo {currentSourcePath}"