title: why git stash cannot abandon the changes made just now?
body: <p>i forked a project from github, and the origin point to my own github repo, remote point to its original repo, since i want to get update from remote, </p>
  
  <p>i use git pull remote branch_name, then my local repo is in conflict mode, 
  now i want to cancel the effect of git pull, so i use git stash, but was surprised to find i failed to do this?  what's wrong?</p>
  
  <p>the detailed info is as follows:</p>
  
  <pre><code>[mirror@home weechat]$ git status
  # On branch master
  # Unmerged paths:
  #   (use "git add/rm &lt;file&gt;..." as appropriate to mark resolution)
  #
  #       both modified:      CMakeLists.txt
  #       both modified:      ChangeLog
  #       both modified:      NEWS
  #       both modified:      configure.in
  #       both modified:      po/cs.po
  #       both modified:      po/de.po
  #       both modified:      po/es.po
  #       both modified:      po/fr.po
  #       both modified:      po/hu.po
  #       both modified:      po/ru.po
  #       both modified:      po/weechat.pot
  #       deleted by us:      src/irc/irc-server.c
  #       both modified:      weechat.spec
  #
  no changes added to commit (use "git add" and/or "git commit -a")
  [mirror@home weechat]$ git stash
  CMakeLists.txt: needs merge
  ChangeLog: needs merge
  NEWS: needs merge
  configure.in: needs merge
  po/cs.po: needs merge
  po/de.po: needs merge
  po/es.po: needs merge
  po/fr.po: needs merge
  po/hu.po: needs merge
  po/ru.po: needs merge
  po/weechat.pot: needs merge
  src/irc/irc-server.c: needs merge
  weechat.spec: needs merge
  CMakeLists.txt: needs merge
  ChangeLog: needs merge
  NEWS: needs merge
  configure.in: needs merge
  po/cs.po: needs merge
  po/de.po: needs merge
  po/es.po: needs merge
  po/fr.po: needs merge
  po/hu.po: needs merge
  po/ru.po: needs merge
  po/weechat.pot: needs merge
  src/irc/irc-server.c: needs merge
  weechat.spec: needs merge
  CMakeLists.txt: unmerged (118d776a202cfc6688290e96fca20ac4f8631f5e)
  CMakeLists.txt: unmerged (d05c9a9711a965dcad0aefa03b79ae7a4f5cb8fb)
  CMakeLists.txt: unmerged (dd2b14cb188e1927e098705d77e922ad530e232b)
  ChangeLog: unmerged (764711936b54aa75812828e1ab15e1632aa3eb9d)
  ChangeLog: unmerged (e00d4bf654c3d199e24bf4910b066f1659fea4b6)
  ChangeLog: unmerged (dbec2315ffc1f15feede248abe3ed85beaa82ed7)
  NEWS: unmerged (457d5443548e6130b50e42a9c87a6f2e8ba4c596)
  NEWS: unmerged (706cee4b8853013f20129ccb2fa9057b7500fceb)
  NEWS: unmerged (33afffbac62399faa32e2560a9accd95dd9a050e)
  configure.in: unmerged (8e1058e5e00a5e671459cee8300420b0488560d9)
  ...
  fatal: git-write-tree: error building trees
  Cannot save the current index state
  </code></pre>
  
  <p>so how to cannel the effect of git pull? should i delete repo, and download it again? </p>