[ocaml-platform] opam update problem

[Shon Feder]

In case this will save some future people some future time:

I seemed to be experiencing a similar, bot not identical problem. 
I had the following setup:

  - OS X: v 10.11
  - OPAM: v 1.2.2_1
  - wget: v 1.13.4

and when I attempted to update opam it looked like this:

```
$ opam update

=-=- Updating package repositories =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=  🐫
[ERROR] Could not update repository default
```

By following this thread, I got as far as running `opam update -vv`, 
but I did not receive the same illuminating information as OP. Instead 
I had this result:

[default: http] Command started
+ wget "--content-disposition" "--no-check-certificate" "-t" "3"
"https://opam.ocaml.org/1.1/urls.txt"
(CWD=/var/folders/45/45fn42f929169glfv0_ngbrw0000gp/T/opam-21935-dd682e)
- Usage: wget [OPTION]... [URL]...
-
- Try `wget --help' for more options.
[ERROR] Could not update repository default 

tbh, I don't know what it was trying to indicate, but I guessed it was 
an issue with wget. I checked http://ftp.gnu.org/gnu/wget/ and learned
wget 1.13.4 was no longer current. So I ran

```
$ brew update
$ brew install wget
```

Which upgraded me to the latest version (1.16.3, at the time I write this).
Afterwards, `opam update` worked without a problem.

Thanks to all you problem solvers in this thread who helped me get this far. :)