title: tortoisehg: kdiff3 doesn't run during merge
body: <p>I am using tortoisehg.</p>
  
  <p>Kdiff3 runs when I select "diff to parent" or "diff to local" from the context menu in the workbench.  However, Kdiff3 doesn't run when merging (merge with local) after a pull.  The merge tool just says the following:
  % hg merge --verbose --tool=internal:merge 2
  resolving manifests
  merging main.c.txt
  warning: conflicts during merge.
  merging main.c.txt incomplete! (edit conflicts, then use 'hg resolve --mark')
  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
  [command returned code 1 Fri Jun 27 13:17:22 2014]</p>
  
  <p>I have selected kdiff3 for both Three-way Merge Tool and Visual Diff Tool in both the global settings and the repository settings.  Is there something else I must do?</p>
  
  <p>Update:  My OS is windows 7</p>
  
  <p>Another Update: (.hgrc in local repo shown below)</p>
  
  <pre><code>[extensions]
  hgext.extdiff =
  
  [extdiff]
  cmd.kdiff3 =
  
  [merge-tools]
  kdiff3.args = $base $local $other -o $output
  </code></pre>
  
  <p>Update 2 (Mercurial.ini):</p>
  
  <pre><code>[merge-tools]
  kdiff3.priority=-1
  kdiff3.args=--L1 base --L2 local --L3 other $base $local $other -o $output
  kdiff3.regkey=Software\KDiff3
  kdiff3.regappend=\kdiff3.exe
  kdiff3.fixeol=True
  kdiff3.gui=True
  </code></pre>
  
  <p>Stephen</p>