Note on resolving nanosecond timestamp issues in Dinghy

Dinghy_test_fixes_for_APFS_notes.md

1. Reviewed How To Open a Homebrew Pull Request

   a. Forked codekitchen/homebrew-dinghy on Github to ms-ati/homebrew-dinghy

   b. Changed to directory containing the Dinghy tap: cd $(brew --repository codekitchen/dinghy)

   c. Added my fork as a remote: git remote add ms-ati https://github.com/ms-ati/homebrew-dinghy.git

   d. Checked out the master branch: git checkout master

   e. Created new branch: git checkout -b use-unfs3-branch-higher-resolution-setattr

   f. See my branch here on github

2. Edited formula to depend on @derfian branch of unfs3: brew edit unfs3

   a. Added devel block to use the new branch:

   ```ruby
   devel do
     url "https://github.com/derfian/unfs3.git", :branch => "higher-resolution-setattr"
     version "0.9.23-pre"
   
     depends_on "autoconf" => :build
     depends_on "automake" => :build
   end
   ```
   

   b. Committed changes and pushed the commits to my remote branch: git push ms-ati use-unfs3-branch-higher-resolution-setattr

   c. Tested the changes per the instructions:

   - `brew tests`
   - `brew uninstall --ignore-dependencies unfs3`
   - `brew install --build-from-source --devel --verbose --debug unfs3`
   - `brew test unfs3` <-- "Error: codekitchen/dinghy/unfs3 defines no test"
   - `brew audit --strict unfs3`
   

   d. Verify that Homebrew thinks the new version is installed:

   $ brew info unfs3
   codekitchen/dinghy/unfs3: stable 0.9.22, devel 0.9.23-pre, HEAD
   User-space NFSv3 server
   http://unfs3.sourceforge.net
   /usr/local/Cellar/unfs3/0.9.23-pre (8 files, 129KB) *
     Built from source on 2018-05-07 at 12:44:11
   From: https://github.com/codekitchen/homebrew-dinghy/blob/master/Formula/unfs3.rb
   ==> Options
   --devel
   	       Install development version 0.9.23-pre
   --HEAD
   	       Install HEAD version

   d. Restarted Dinghy to pick up the new changes: dinghy down; dinghy up

   e. Reviewed system calls made by unfsd (need to come back to this after other changes done)

   ```bash
   sudo dtruss -n unfsd
   ...
   ```
   

   f. Observed that edited files still having timestamps set to zero-nanoseconds:

   ```bash
   $ brew install coreutils
   $ gls --full-time ~/Desktop/NOTES.md
   
   -rw-r--r-- 1 marcsiegel staff 2297 2018-05-07 14:00:34.000000000 -0400 /Users/marcsiegel/Desktop/NOTES.md
                                                          ^^^^^^^^^
   ```
   

3. Modify Dinghy to support the nanosecond timestamps

   a. Fork codekitchen/dinghy on Github to ms-ati/dinghy

   b. Create branch git checkout -b support-nanosecond-timestamps-on-apfs