Support for Google Play books without metadata node

calibre-plugin/libadobeFulfill.py

@@ -319,6 +319,7 @@ def fulfill(acsm_file, do_notify = False):
     adNS = lambda tag: '{%s}%s' % ('http://ns.adobe.com/adept', tag)
     dcNS = lambda tag: '{%s}%s' % ('http://purl.org/dc/elements/1.1/', tag)
 
+    try: 
         mimetype = acsmxml.find("./%s/%s/%s" % (adNS("resourceItemInfo"), adNS("metadata"), dcNS("format"))).text
 
         if (mimetype == "application/pdf"):
@@ -331,6 +332,10 @@ def fulfill(acsm_file, do_notify = False):
             print("Weird mimetype: %s" % (mimetype))
             print("Continuing anyways ...")
         
+    except: 
+        # Some books, like from Google Play books, use a different format and don't have that metadata tag.
+        pass
+
 
     fulfill_request, adept_ns = buildFulfillRequest(acsmxml)