Merged revisions 104082 via svnmerge from

https://origsvn.digium.com/svn/asterisk/branches/1.4

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r104082 | file | 2008-02-25 11:17:18 -0400 (Mon, 25 Feb 2008) | 6 lines

Due to recent changes tag will no longer be NULL if not present so we have to use ast_strlen_zero to see if it's actually blank.
(closes issue #12061)
Reported by: flefoll
Patches:
      chan_sip.c.br14.patch_pedantic_no_totag uploaded by flefoll (license 244)

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git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@104083 65c4cc65-6c06-0410-ace0-fbb531ad65f3