docker: Fix Docker development environment unicode handling.
docker: Fix Docker development environment unicode handling.

Fixes #11323.

Thanks to xiamingplus for the report and debugging.

eeshangarg/zulip,hackerkid/zulip,shubhamdhama/zulip,zulip/zulip,hackerkid/zulip,tommyip/zulip,brainwane/zulip,hackerkid/zulip,timabbott/zulip,timabbott/zulip,andersk/zulip,synicalsyntax/zulip,shubhamdhama/zulip,eeshangarg/zulip,andersk/zulip,rishig/zulip,synicalsyntax/zulip,punchagan/zulip,kou/zulip,punchagan/zulip,eeshangarg/zulip,showell/zulip,brainwane/zulip,showell/zulip,hackerkid/zulip,punchagan/zulip,rht/zulip,tommyip/zulip,synicalsyntax/zulip,synicalsyntax/zulip,zulip/zulip,shubhamdhama/zulip,synicalsyntax/zulip,andersk/zulip,showell/zulip,rishig/zulip,synicalsyntax/zulip,tommyip/zulip,timabbott/zulip,andersk/zulip,showell/zulip,rishig/zulip,brainwane/zulip,kou/zulip,rishig/zulip,rht/zulip,rht/zulip,eeshangarg/zulip,andersk/zulip,tommyip/zulip,kou/zulip,timabbott/zulip,kou/zulip,zulip/zulip,brainwane/zulip,brainwane/zulip,timabbott/zulip,hackerkid/zulip,tommyip/zulip,andersk/zulip,zulip/zulip,tommyip/zulip,rht/zulip,rht/zulip,kou/zulip,timabbott/zulip,hackerkid/zulip,eeshangarg/zulip,zulip/zulip,shubhamdhama/zulip,punchagan/zulip,eeshangarg/zulip,eeshangarg/zulip,punchagan/zulip,timabbott/zulip,rht/zulip,zulip/zulip,rishig/zulip,showell/zulip,hackerkid/zulip,zulip/zulip,punchagan/zulip,punchagan/zulip,kou/zulip,showell/zulip,kou/zulip,rht/zulip,tommyip/zulip,shubhamdhama/zulip,rishig/zulip,brainwane/zulip,synicalsyntax/zulip,andersk/zulip,shubhamdhama/zulip,shubhamdhama/zulip,rishig/zulip,showell/zulip,brainwane/zulip