serials importer: remove substrings only from the end of the title

* closes #923

cds_ils/importer/providers/utils.py

@@ -108,3 +108,10 @@ def rreplace(s, old, new, occurrence=1):
     """Reverse replace."""
     li = s.rsplit(old, occurrence)
     return new.join(li)
+
+
+def rreplace_end(s, old):
+    """Replace only if the substring `old` is at the end of the string `s`."""
+    if s.endswith(old):
+        return s[: -len(old)]
+    return s

cds_ils/importer/series/importer.py

@@ -20,7 +20,7 @@
 from invenio_db import db
 
 from cds_ils.importer.errors import SeriesImportError
-from cds_ils.importer.providers.utils import rreplace
+from cds_ils.importer.providers.utils import rreplace, rreplace_end
 from cds_ils.importer.series.api import (
     search_series_by_isbn,
     search_series_by_issn,
@@ -120,7 +120,7 @@ def _normalize_title(title):
         # will become
         # `international series of numerical mathematics`
         for substring in IGNORE_SUFFIXES:
-            t = rreplace(t, substring, "")
+            t = rreplace_end(t, substring)
         return t.strip()
 
     def update_series(self, matched_series, json_series):