Merged revisions 305252 via svnmerge from

Merged revisions 305252 via svnmerge from
https://origsvn.digium.com/svn/asterisk/branches/1.4

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  r305252 | qwell | 2011-01-31 16:56:54 -0600 (Mon, 31 Jan 2011) | 10 lines

  Prevent a crash when dialing a technology with no destination (ex: Dial(SIP/))

  chan_iax2 and other channel drivers already had code to prevent this.  The
  attempt that app_dial was making to prevent it was not correct, so I fixed that.

  (closes issue #18371)
  Reported by: gbour
  Patches:
        18371.patch uploaded by gbour (license 1162)
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git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.6.2@305253 65c4cc65-6c06-0410-ace0-fbb531ad65f3