[server/test] add test for db-dump command

[server] fix db-dump with sqlite 'gzip -c dbname > backupfile' needs to go through the shell.

[serverctl] fix db-dump Since changeset af47954c1015 we would die with: AttributeError: 'ServerMigrationHelper' object has no attribute 'repo'

[server/test] sorting vs dict vs python3

[devtools] more sorted() vs dict vs python3

[web/application] return bytes from redirect_handler and validation_error_handler

[devtools] fix ResourceWarning: unclosed file tmpdb-__default_empty_db__.config

[serverconfig] fix ResourceWarning: unclosed file bootstrap_cubes

Use cubicweb._

[syncschema] hashlib.md5() wants bytes

[server/test] use next() builtin instead of next() method

[server/test] dict.iterkeys

[syncschema] don't arbitrarily remove constraints from the in-memory schema For some constraint types, it may make sense to have several constraints of that type simultaneously. In such a case, removing one of them from the in-memory schema is wrong. Closes #7446353

[server/test] don't leak timeout from one test class to the next Reset SQL_CONNECT_HOOKS after we're done with this test class so the next one doesn't inherit a timeout it doesn't want.

[server/test] CWAttribute.extra_props is Bytes

[dataimport] give unicode objects to psycopg2 copy_from

[dataimport] extid must be a bytes object

[dataimport] import StringIO from io

[dataimport] fix ucsvreader for python3 The csv module in python3 wants str, so use a StreamReader to feed csv.reader and don't decode the output

[server/test] import StringIO from io on python3 Don't change the import for python2, as we print a mix of unicode and str.

[server/datafeed] drop URLLibResponseAdapter.info I don't know where it's used

[devtools] pass a key to sort() method python3 dicts are not comparable

[postcreate] properly set is_instance_of for bootstrap entities Entities created before CWEType itself need the is/is_instance_of relations created later. We were actually only inserting "is". Closes #7656606.

[migration] re-try without print_function when compiling a script fails As part of the python3 porting we added the __future__.print_function import to cubicweb.migration. That started affecting all migration scripts it runs, which may not be prepared. So if compiling a script results in SyntaxError, try again without the print_function flag. Closes #7935030

[test] do not overwrite user's CW_CUBES_PATH in unittest_migration Currently when you rely on your CW_CUBES_PATH environment variable to locate cubes necessary for cubicweb's tests, the migration test crashes because it overrides the env var.

[server/test] dict.itervalues() → iter(dict.values())

make sync_schema_props_perms(<computed rtype>) work as expected It currently ends up with an ExecutionError while we want to synchronize permissions. This makes 3.21.1 migration of any application using computed relation crashing. Also, remove pre 3.6 compat code in hooks that prevent living schema update on computed relation's permission changes.

[web/http_headers] use classmethod decorator

[schema] use classmethod decorator

[devtools] delete postgresql socket directory after killing the server ... or when failing to start it.