Fix i18n: message catalogs are not compiled when specific build (refs: #4560)

sphinx-build skips message catalog builds if specific filename are given
as arguments.

CHANGES

@@ -20,6 +20,8 @@ Bugs fixed
 * #4531: autosummary: methods are not treated as attributes
 * #4538: autodoc: ``sphinx.ext.autodoc.Options`` has been moved
 * #4539: autodoc emits warnings for partialmethods
+* i18n: message catalogs are not compiled if specific filenames are given for
+  ``sphinx-build`` as arguments (refs: #4560)
 
 Testing
 --------

sphinx/builders/__init__.py

@@ -16,7 +16,7 @@ from docutils import nodes
 
 from sphinx.deprecation import RemovedInSphinx20Warning
 from sphinx.environment.adapters.asset import ImageAdapter
-from sphinx.util import i18n, path_stabilize, logging, status_iterator
+from sphinx.util import i18n, logging, status_iterator
 from sphinx.util.console import bold  # type: ignore
 from sphinx.util.i18n import find_catalog
 from sphinx.util.osutil import SEP, ensuredir, relative_uri
@@ -255,11 +255,14 @@ class Builder(object):
         # type: (List[unicode]) -> None
         def to_domain(fpath):
             # type: (unicode) -> unicode
-            docname, _ = path.splitext(path_stabilize(fpath))
-            dom = find_catalog(docname, self.config.gettext_compact)
-            return dom
+            docname = self.env.path2doc(path.abspath(fpath))
+            if docname:
+                return find_catalog(docname, self.config.gettext_compact)
+            else:
+                return None
 
         specified_domains = set(map(to_domain, specified_files))
+        specified_domains.discard(None)
         catalogs = i18n.find_catalog_source_files(
             [path.join(self.srcdir, x) for x in self.config.locale_dirs],
             self.config.language,

tests/test_catalogs.py

@@ -65,7 +65,7 @@ def test_compile_specific_catalogs(app, status, warning):
         return set(find_files(catalog_dir, '.mo'))
 
     actual_on_boot = get_actual()  # sphinx.mo might be included
-    app.builder.compile_specific_catalogs(['admonitions'])
+    app.builder.compile_specific_catalogs([app.srcdir / 'admonitions.txt'])
     actual = get_actual() - actual_on_boot
     assert actual == set(['admonitions.mo'])