title: Unable to self-update Composer
body: <p>I am trying to update Composer without any luck!</p>
  <p>What I have tried:</p>
  <pre><code>$ composer self-update
  </code></pre>
  <blockquote>
  <p>[InvalidArgumentException]
  Command &quot;self-update&quot; is not defined.</p>
  </blockquote>
  <pre><code>$ sudo -H composer self-update
  </code></pre>
  <blockquote>
  <p>[InvalidArgumentException]
  Command &quot;self-update&quot; is not defined.</p>
  </blockquote>
  <pre><code>$ sudo apt-get install composer
  </code></pre>
  <blockquote>
  <p>Reading package lists... Done Building dependency tree        Reading
  state information... Done composer is already the newest version. The
  following packages were automatically installed and are no longer
  required:   libntdb1 linux-headers-4.2.0-30
  linux-headers-4.2.0-30-generic linux-image-4.2.0-30-generic
  linux-image-extra-4.2.0-30-generic python-ntdb Use 'apt-get
  autoremove' to remove them. 0 upgraded, 0 newly installed, 0 to remove
  and 10 not upgraded.</p>
  </blockquote>
  <p>I am trying to self-update Composer because I am facing the following each time I try:</p>
  <pre><code>$ composer update
  </code></pre>
  <blockquote>
  <p>Loading composer repositories with package information Updating
  dependencies (including require-dev)
  [RuntimeException]
  Could not load package rmrevin/yii2-fontawesome in
  <a href="http://packagist.org" rel="noreferrer">http://packagist.org</a>: [UnexpectedValueException] Could not parse
  version constraint v4.1     .<em>: Invalid version string &quot;v4.1.</em>&quot;
  [UnexpectedValueException]
  Could not parse version constraint v4.1.<em>: Invalid version string
  &quot;v4.1.</em>&quot;</p>
  </blockquote>
  <p>How can I fix this issue?</p>
  <p>My PHP version is:</p>
  <pre><code>php --version
  </code></pre>
  <blockquote>
  <p>PHP 5.6.11-1ubuntu3.4 (cli)  Copyright (c) 1997-2015 The PHP Group
  Zend Engine v2.6.0, Copyright (c) 1998-2015 Zend Technologies
  with Zend OPcache v7.0.6-dev, Copyright (c) 1999-2015, by Zend Technologies</p>
  </blockquote>
  <p>My composer version is:</p>
  <pre><code>composer --version
  </code></pre>
  <blockquote>
  <p>Composer version @package_branch_alias_version@ (@package_version@)
  @release_date@</p>
  </blockquote>