Fix #1617 (pdftrim bad error checking)

src/calibre/ebooks/pdf/pdftrim.py

@@ -50,12 +50,16 @@ def main(args=sys.argv):
     except:
         print "Unable to read input"
         return 2
+    title   = _('Unknown')
+    author  = _('Unknown')
+    try:
         info = input_pdf.getDocumentInfo()
-    title   = 'Unknown'
-    author  = 'Unknown'
         if info.title:
             title   = info.title
+        if info.author:
             author  = info.author
+    except:
+        pass
     if opts.bounding != None:
         try:
             bounding = open( opts.bounding , 'r' )