Add instrumentation to debug I/O error in CI that I don't get locally

try to debug 'sqlite3.OperationalError: disk I/O error' failures:

  https://github.com/roundup-tracker/roundup/actions/runs/2995869962

  https://app.travis-ci.com/github/roundup-tracker/roundup/jobs/581894108

during commit().

Get info on mode, uid, gid etc. for db directory and files in it.

I can provoke the failure by stopping before a self.conn.commit(),
chmod 555 the directory holding the db then continue. But even running
a full test suite I never see this error. It only occurs for some
tests and not others and doesn't seem to be consistent.

One other possible workaround is setting it to WAL mode rather than
journal mode when opening it.

Author: rouilj

roundup/backends/back_sqlite.py

@@ -418,11 +418,39 @@ def sql_commit(self):
 
             Ignore errors if there's nothing to commit.
         """
+        def list_dir(dir):
+            import os
+            files = os.listdir(self.dir)
+                # ['db-journal', 'files', 'db']
+            for entry in [''] + files:
+                path = self.dir + '/' + entry
+                stat = os.stat(path)
+                print("file: %s, uid: %s, gid: %s, mode: %o"%(path,
+                                    stat.st_uid, stat.st_gid, stat.st_mode))
+
+        # Getting sqlite3.OperationalError: disk I/O error
+        # in CI. It happens intermittently. Try to get more
+        # info about what is happening and retry the commit.
+        # Some possibilities:
+        #       -journal file not writable
+        #       file has disappeared
+        #
+        # Note after exception self.conn.in_transaction is False
+        # but was True before failed commit(). Retry succeeds,
+        # but I am not sure it actually does anything.
+        # for retry in range(2):
         try:
             self.conn.commit()
+        except sqlite.OperationalError as error:
+            if str(error) != 'disk I/O error':
+                raise
+            list_dir(self.dir)
+            raise
         except sqlite.DatabaseError as error:
             if str(error) != 'cannot commit - no transaction is active':
                 raise
+        #   else:
+        #       break # out of loop if no exception
         # open a new cursor for subsequent work
         self.cursor = self.conn.cursor()