Fish shell auto completions do not appear to be working on 2.5.2 on MacOS

#### To report a bug...

* What command(s) did you run?
all the normal shell completions that work fine on taskwarrior 2.5.1 on ubuntu 18.04 do not seem to work at all on mac os 10.14.4

* What did you expect to happen?
* What actually happened?
* Paste the output of the

```

task 2.5.2
Platform: Darwin

Compiler
Version: 4.2.1 Compatible Apple LLVM 10.0.0 (clang-1000.11.45.5)
Caps: +stdc +stdc_hosted +LP64 +c8 +i32 +l64 +vp64 +time_t64
Compliance: C++14

Build Features
Built: Mar 4 2019 14:46:58
Commit: b87703eb
CMake: 3.13.4
libuuid: libuuid + uuid_unparse_lower
libgnutls: 3.6.6
Build type: release

Configuration
File: /Users/david/.taskrc (found), 16239 bytes, mode 100644
Data: /Users/david/.task (found), dir, mode 40755
Locking: Enabled
GC: Enabled
$EDITOR: vim
Server: taskwarrior.inthe.am:53589
CA: ~/.task/ca.cert.pem, readable, 2405 bytes
Certificate: ~/.task/private.certificate.pem, readable, 2462 bytes
Key: ~/.task/private.key.pem, readable, 3660 bytes
Trust: ignore hostname
Ciphers: NORMAL
Creds: inthe_am/daveparkinson/************************************

Hooks
System: Enabled
Location: /Users/david/.task/hooks
Active: on-modify.timetracking (executable) (symlink)
on-modify.timewarrior (executable)
Inactive:

Tests
Terminal: 120x30
Dups: Scanned 2155 tasks for duplicate UUIDs:
Found duplicate 794cb7c5-7a6f-4896-b159-363cdfdb1b37
Found duplicate adb205f5-9b1f-4e0e-9f40-0da0cfefa1b8
Found duplicate e146c9f6-a041-4e60-8001-8afdad647f78
Found duplicate 7d00c2bb-8234-40de-8c4f-c9d455ca93c2
Found duplicate d502976d-7d04-4894-bef5-ce66ce358bc7
Found duplicate f2904c17-1bf7-424b-a586-185fa6ac5125
Found duplicate a9a96e75-f44e-4c7c-a99f-48b2fa06b00b
Found duplicate a4ac48a1-404e-46a8-a5fb-623328935047
Found duplicate 0459bf6a-dd14-4121-bef2-b68940d86f71
Found duplicate 9bfb20ef-1726-457e-9c5d-9a92d8c7c355
Found duplicate a9a96e75-f44e-4c7c-a99f-48b2fa06b00b
Found duplicate 5db7fa90-f4bf-48ae-a98b-f101e0573d1b
Found duplicate fa07600c-945a-4335-916a-b6a82367263b
Found duplicate b82e8fa3-2cee-46c0-bfc8-44e42263e3b4
Found duplicate 7d4d0641-57f8-488a-8e17-ccb74e4aa869
Found duplicate e1463bab-1247-42fb-ad6d-ea7fa0bbfcc1
Found duplicate 25c8fbbe-be7e-4909-ae60-cf0376c0fa2a
Found duplicate 953507db-cc01-4540-b92c-c69ee8c90e55
Found duplicate 625c6f1b-c2d7-4c96-8091-0e8c62ac2408
Broken ref: Scanned 2155 tasks for broken references:
No broken references found

```