Removed ancient and unused code to find the last imported revision from previous imports

to use for the current import by looking at the p4 tags. The current approach of using
the log message works better.

Signed-off-by: Simon Hausmann <simon@lst.de>

contrib/fast-import/git-p4

@@ -895,23 +895,6 @@ class P4Sync(Command):
         if self.detectLabels:
             self.getLabels();
 
-        if len(self.changeRange) == 0:
-            try:
-                sout, sin, serr = popen2.popen3("git name-rev --tags `git rev-parse %s`" % self.branch)
-                output = sout.read()
-                if output.endswith("\n"):
-                    output = output[:-1]
-                tagIdx = output.index(" tags/p4/")
-                caretIdx = output.find("^")
-                endPos = len(output)
-                if caretIdx != -1:
-                    endPos = caretIdx
-                self.rev = int(output[tagIdx + 9 : endPos]) + 1
-                self.changeRange = "@%s,#head" % self.rev
-                self.initialParent = parseRevision(self.branch)
-            except:
-                pass
-
         self.tz = "%+03d%02d" % (- time.timezone / 3600, ((- time.timezone % 3600) / 60))
 
         importProcess = subprocess.Popen(["git", "fast-import"], stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE);