utils_extra check_value url quote on n3 fail

if we receive a string that we think should be a url then check to see
if rdflib can safely serialize it, on failure, url quote it

this is not efficient but it is at least somewhat safe

note that uri dealiasing has to be done to be able to do a full
comparison between uris to determine if they even have a chance of being
the same uri, so this is just another layer in that where the escape
sequences have to be undone as one step along the way to finding the
canonical represenation of the uri

pyontutils/utils_extra.py

@@ -2,6 +2,7 @@
     Reused utilties that depend on packages outside the python standard library.
 """
 import hashlib
+from urllib.parse import quote as url_quote
 import rdflib
 
 
@@ -15,7 +16,18 @@ def check_value(v):
     if isinstance(v, rdflib.Literal) or isinstance(v, rdflib.URIRef):
         return v
     elif isinstance(v, str) and v.startswith('http'):
-        return rdflib.URIRef(v)
+        # FIXME this is dumb and dangerous but whatever
+        uri = rdflib.URIRef(v)
+        try:
+            uri.n3()
+        except:
+            # dois allow ... non-url and non-identifier chars
+            # that must be escaped or we have to use strings
+            # FIXME this WILL induce an aliasing problem if
+            # another process quotes using a different rule
+            uri = rdflib.URIRef(url_quote(v, ':/;()'))
+
+        return uri
     else:
         return rdflib.Literal(v)