fetchzip, fetchgit: cleanup handling of optional features and whitespace

No intended functional difference, just trying to polish to make this easier to
extend and more aligned with other nix conventions.

pkgs/build-support/fetchgit/default.nix

@@ -1,4 +1,4 @@
-{stdenvNoCC, git, cacert}: let
+{ stdenvNoCC, git, cacert }: let
   urlToName = url: rev: let
     inherit (stdenvNoCC.lib) removeSuffix splitString last;
     base = last (splitString ":" (baseNameOf (removeSuffix "/" url)));

pkgs/build-support/fetchgit/nix-prefetch-git

@@ -1,6 +1,5 @@
-#! /usr/bin/env bash
-
-set -e -o pipefail
+#!/usr/bin/env bash
+set -eo pipefail
 
 url=
 rev=
@@ -40,9 +39,9 @@ usage(){
 Options:
       --out path         Path where the output would be stored.
       --url url          Any url understood by 'git clone'.
-      --rev ref       Any sha1 or references (such as refs/heads/master)
+      --rev ref          Any sha1 or references (such as refs/heads/master).
       --hash h           Expected hash.
-      --branch-name   Branch name to check out into
+      --branch-name      Branch name to check out into.
       --deepClone        Clone the entire repository.
       --no-deepClone     Make a shallow clone of just the required ref.
       --leave-dotGit     Keep the .git directories.

pkgs/build-support/fetchzip/default.nix

@@ -5,24 +5,22 @@
 # (e.g. due to minor changes in the compression algorithm, or changes
 # in timestamps).
 
-{ fetchurl, unzip }:
+{ lib, fetchurl, unzip }:
 
-{ # Optionally move the contents of the unpacked tree up one level.
-  stripRoot ? true
+{ name ? "source"
 , url
+  # Optionally move the contents of the unpacked tree up one level.
+, stripRoot ? true
 , extraPostFetch ? ""
-, name ? "source"
 , ... } @ args:
 
 (fetchurl ({
   inherit name;
 
   recursiveHash = true;
-
   downloadToTemp = true;
 
-  postFetch =
-    ''
+  postFetch = ''
     unpackDir="$TMPDIR/unpack"
     mkdir "$unpackDir"
     cd "$unpackDir"
@@ -30,22 +28,23 @@
     renamed="$TMPDIR/${baseNameOf url}"
     mv "$downloadedFile" "$renamed"
     unpackFile "$renamed"
+    result=$unpackDir
   ''
-    + (if stripRoot then ''
+  # Most src disted tarballs have a parent directory like foo-1.2.3/ to strip
+  + lib.optionalString stripRoot ''
     if [ $(ls "$unpackDir" | wc -l) != 1 ]; then
       echo "error: zip file must contain a single file or directory."
       echo "hint: Pass stripRoot=false; to fetchzip to assume flat list of files."
       exit 1
     fi
     fn=$(cd "$unpackDir" && echo *)
-      if [ -f "$unpackDir/$fn" ]; then
+    result="$unpackDir/$fn"
+  '' + ''
     mkdir $out
-      fi
-      mv "$unpackDir/$fn" "$out"
-    '' else ''
-      mv "$unpackDir" "$out"
-    '') #*/
+    mv "$result" "$out"
+  ''
   + extraPostFetch;
+
 } // removeAttrs args [ "stripRoot" "extraPostFetch" ])).overrideAttrs (x: {
   # Hackety-hack: we actually need unzip hooks, too
   nativeBuildInputs = x.nativeBuildInputs ++ [ unzip ];