pginstaller - pginst: Fix the check for an existing installation.

Log Message:
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Fix the check for an existing installation.

Modified Files:
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pginst/wrapper:
wrapper.proj (r1.3 -> r1.4)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pginstaller/pginst/wrapper/wrapper.proj.diff?r1=1.3&r2=1.4)
wrapper.wxs (r1.8 -> r1.9)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pginstaller/pginst/wrapper/wrapper.wxs.diff?r1=1.8&r2=1.9)