<p dir="auto">I know that this has been reported before, I've read all issues about this bug, but all of them are for 2.x and previous versions, and the newest bug reported is about 1 year's old.</p>
<p dir="auto">However this bug is still present on bootstrap 3.0.1. I've made a test case to reproduce it, and a possible fix to it.</p>
<h3 dir="auto">The issue</h3>
<p dir="auto">Here you can see the issue (screenshot)<br>
<a href="https://www.dropbox.com/s/bns0wdl6cmzgmzr/Screenshot%20at%202013-11-04%2010%3A55%3A36.png" rel="nofollow">https://www.dropbox.com/s/bns0wdl6cmzgmzr/Screenshot%20at%202013-11-04%2010%3A55%3A36.png</a></p>
<p dir="auto">Here you can see the real test case:<br>
<a href="https://dl.dropboxusercontent.com/u/1715488/bootstrap/btn-height-test.html" rel="nofollow">https://dl.dropboxusercontent.com/u/1715488/bootstrap/btn-height-test.html</a></p>
<h3 dir="auto">Bug fix proposal</h3>
<p dir="auto">I've removed vertical paddings. Instead, I've fixed button's height and line-height. It's been done inside of button-size(...) mixins, this is the result:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="// Button sizes
// -------------------------
.button-size(@padding-vertical; @padding-horizontal; @font-size; @line-height; @border-radius) {
  @line-height-computed: floor(@font-size * @line-height); // ~20px
  // forzamos el height
  @btn-height: @line-height-computed + 2 * @padding-vertical + 2;

  padding: 0 @padding-horizontal;
  font-size: @font-size;
  line-height: @btn-height - 2;
  height: @btn-height;
  border-radius: @border-radius;
}"><pre class="notranslate"><code class="notranslate">// Button sizes
// -------------------------
.button-size(@padding-vertical; @padding-horizontal; @font-size; @line-height; @border-radius) {
  @line-height-computed: floor(@font-size * @line-height); // ~20px
  // forzamos el height
  @btn-height: @line-height-computed + 2 * @padding-vertical + 2;

  padding: 0 @padding-horizontal;
  font-size: @font-size;
  line-height: @btn-height - 2;
  height: @btn-height;
  border-radius: @border-radius;
}
</code></pre></div>
<p dir="auto">Screenshot:<br>
<a href="https://www.dropbox.com/s/i8l0kj85xju315q/Screenshot%20at%202013-11-04%2011%3A07%3A09.png" rel="nofollow">https://www.dropbox.com/s/i8l0kj85xju315q/Screenshot%20at%202013-11-04%2011%3A07%3A09.png</a></p>
<p dir="auto">Test case:<br>
<a href="https://dl.dropboxusercontent.com/u/1715488/bootstrap/btn-height-fix.html" rel="nofollow">https://dl.dropboxusercontent.com/u/1715488/bootstrap/btn-height-fix.html</a></p>
<h3 dir="auto">Notes</h3>
<p dir="auto">I've only tested in chrome, firefox and opera for linux, and only in desktops, but I've been using this method of  "zero vertical paddings" for buttons since a few years with excelent results.<br>
In fact I've been using bootstrap since 2.0 and I've always applied a patch to fix this (using this method) without any regressions or other issues, and I know that works ok in windows browsers, ios, and android browsers, but as I said I didn't make any serious test with them.</p>
<div class="highlight highlight-text-html-basic notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="&lt;div class=&quot;col-lg-6&quot;&gt;
    &lt;div class=&quot;input-group&quot;&gt;
      &lt;input type=&quot;text&quot; class=&quot;form-control input-large&quot;&gt;
      &lt;span class=&quot;input-group-btn&quot;&gt;
        &lt;button class=&quot;btn btn-default btn-large&quot; type=&quot;button&quot;&gt;Go!&lt;/button&gt;
      &lt;/span&gt;
    &lt;/div&gt;&lt;!-- /input-group --&gt;
&lt;/div&gt;&lt;!-- /.col-lg-6 --&gt;"><pre class="notranslate"><span class="pl-kos">&lt;</span><span class="pl-ent">div</span> <span class="pl-c1">class</span>="<span class="pl-s">col-lg-6</span>"<span class="pl-kos">&gt;</span>
    <span class="pl-kos">&lt;</span><span class="pl-ent">div</span> <span class="pl-c1">class</span>="<span class="pl-s">input-group</span>"<span class="pl-kos">&gt;</span>
      <span class="pl-kos">&lt;</span><span class="pl-ent">input</span> <span class="pl-c1">type</span>="<span class="pl-s">text</span>" <span class="pl-c1">class</span>="<span class="pl-s">form-control input-large</span>"<span class="pl-kos">&gt;</span>
      <span class="pl-kos">&lt;</span><span class="pl-ent">span</span> <span class="pl-c1">class</span>="<span class="pl-s">input-group-btn</span>"<span class="pl-kos">&gt;</span>
        <span class="pl-kos">&lt;</span><span class="pl-ent">button</span> <span class="pl-c1">class</span>="<span class="pl-s">btn btn-default btn-large</span>" <span class="pl-c1">type</span>="<span class="pl-s">button</span>"<span class="pl-kos">&gt;</span>Go!<span class="pl-kos">&lt;/</span><span class="pl-ent">button</span><span class="pl-kos">&gt;</span>
      <span class="pl-kos">&lt;/</span><span class="pl-ent">span</span><span class="pl-kos">&gt;</span>
    <span class="pl-kos">&lt;/</span><span class="pl-ent">div</span><span class="pl-kos">&gt;</span><span class="pl-c">&lt;!-- /input-group --&gt;</span>
<span class="pl-kos">&lt;/</span><span class="pl-ent">div</span><span class="pl-kos">&gt;</span><span class="pl-c">&lt;!-- /.col-lg-6 --&gt;</span></pre></div>
<p dir="auto">Height of .input-large and .btn-large is different by 1px in Chrome. Giving <strong>height: 56px</strong> to <strong>.btn-large</strong> helps.</p>