Fixes version conflicts when building between special&non-special.

Refs #289. Aporia still cannot be installed. In addition,
the myVersion vs. version should be refactored into version vs.
specialVersion.

tests/issue289/issue289.nim

@@ -0,0 +1 @@
+echo 42

tests/issue289/issue289.nimble

@@ -0,0 +1,14 @@
+# Package
+
+version       = "0.1.0"
+author        = "Dominik Picheta"
+description   = "Package reproducing issues depending on #head and concrete version of the same package."
+license       = "MIT"
+
+bin = @["issue289"]
+
+# Dependencies
+
+requires "nim >= 0.15.3", "https://github.com/nimble-test/packagea.git 0.6.0"
+requires "https://github.com/nimble-test/packagea.git#head"
+

tests/tester.nim

@@ -41,6 +41,14 @@ proc inLines(lines: seq[string], line: string): bool =
   for i in lines:
     if line.normalize in i.normalize: return true
 
+test "can build with #head and versioned package (#289)":
+  # Clear nimble dir.
+  removeDir(installDir)
+  createDir(installDir)
+
+  cd "issue289":
+    check execNimble(["install", "-y"]).exitCode == QuitSuccess
+
 test "can validate package structure (#144)":
   # Clear nimble dir.
   removeDir(installDir)