Handle translations, update RELEASE NOTES

Ignore patches that only update the po files unless translations should
be built.

Update release information for 0.19.

Change-Id: I587688d207d244e72e1fc035d4fe5d72a1b5da88

RELEASE_NOTES.rst

@@ -1,8 +1,16 @@
 Release notes
 =============
 
+0.19
+----
+
+* ``openstack-doc-test``: Optimize translation imports, improve output
+  messages.
+* ``autohelp.py``: Improve sanitizer.
+
 0.18.1
 ------
+
 * Fix ``doc-tools-check-languages`` to handle all repositories and
   setups.
 

os_doc_tools/doctest.py

@@ -319,6 +319,27 @@ def www_touched():
     return www_changed and not other_changed
 
 
+def only_po_touched():
+    """Check whether only files in locale directory are touched."""
+
+    try:
+        git_args = ["git", "diff", "--name-only", "HEAD~1", "HEAD"]
+        modified_files = check_output(git_args).strip().split()
+    except (subprocess.CalledProcessError, OSError) as e:
+        print("git failed: %s" % e)
+        sys.exit(1)
+
+    locale_changed = False
+    other_changed = False
+    for f in modified_files:
+        if "/locale/" in f and f.endswith((".po", ".pot")):
+            locale_changed = True
+        else:
+            other_changed = True
+
+    return locale_changed and not other_changed
+
+
 def check_modified_affects_all(rootdir):
     """Check whether special files were modified.
 
@@ -1447,6 +1468,10 @@ def doctest():
         print("Only files in www directory changed, nothing to do.\n")
         return
 
+    if not CONF.force and not CONF.language and only_po_touched():
+        print("Only files in locale directories changed, nothing to do.\n")
+        return
+
     if CONF.check_syntax or CONF.check_niceness or CONF.check_links:
         if CONF.force:
             errors += validate_all_files(doc_path, FILE_EXCEPTIONS,