[damned-lies] Avoid producing 500 errors for msginit failures

[Claude Paroz <claudep src gnome org>]

commit d8250fd0754f2b31eb33559ed9abd867e1aca1ee
Author: Claude Paroz <claude 2xlibre net>
Date:   Mon Jan 17 09:01:19 2022 +0100

    Avoid producing 500 errors for msginit failures

 stats/tests/tests.py | 16 ++++++++++++++++
 stats/views.py       |  9 +++++++--
 2 files changed, 23 insertions(+), 2 deletions(-)
---
diff --git a/stats/tests/tests.py b/stats/tests/tests.py
index 1b8a0130..387e415a 100644
--- a/stats/tests/tests.py
+++ b/stats/tests/tests.py
@@ -374,6 +374,22 @@ class ModuleTestCase(TestCase):
         )
         self.assertContains(response, '# Tamil translation for gnome-hello.')
 
+    @test_scratchdir
+    def test_dynamic_po_msginit_error(self):
+        tamil = Language.objects.create(name="Tamil", locale="ta")
+        with PatchShellCommand(only=['git ']):
+            self.branch.update_stats(force=False)  # At least POT stats needed
+        pot_stats = Statistics.objects.get(
+            branch=self.branch, domain__name='po', language__isnull=True
+        )
+        dyn_url = FakeLangStatistics(pot_stats, tamil).po_url()
+        with patch('stats.views.run_shell_command', side_effect=OSError()):
+            response = self.client.get(dyn_url)
+        self.assertContains(
+            response,
+            "Unable to produce a new .po file for language ta"
+        )
+
     @test_scratchdir
     def test_commit_ability(self):
         branch = self.mod.get_head_branch()
diff --git a/stats/views.py b/stats/views.py
index ad6736b8..97a0f3dd 100644
--- a/stats/views.py
+++ b/stats/views.py
@@ -231,8 +231,13 @@ def dynamic_po(request, module_name, branch_name, domain_name, filename):
     else:
         dyn_content += "# FIRST AUTHOR <EMAIL@ADDRESS>, YEAR.\n#\n"
 
-    command = "msginit --locale=%s --no-translator --input=%s --output-file=-" % (locale, file_path)
-    status, output, err = run_shell_command(command, raise_on_error=True)
+    command = f"msginit --locale={locale} --no-translator --input={file_path} --output-file=-"
+    try:
+        status, output, err = run_shell_command(command, raise_on_error=True)
+    except OSError:
+        return HttpResponse(
+            f"Unable to produce a new .po file for language {locale}, msginit command failed."
+        )
     lines = output.split("\n")
     skip_next_line = False
     for i, line in enumerate(lines):