You can check if a PO file is valid with the following command:

        msgfmt -c -o /dev/null <po file>
      

The following errors were found in rustc 's PO files:

gettext: src/doc/rust-by-example/po/es.po:994: 'msgid' and 'msgstr' entries do not both end with '\n'
src/doc/rust-by-example/po/es.po:1580: 'msgid' and 'msgstr' entries do not both end with '\n'
src/doc/rust-by-example/po/es.po:1603: 'msgid' and 'msgstr' entries do not both end with '\n'
src/doc/rust-by-example/po/es.po:1671: 'msgid' and 'msgstr' entries do not both end with '\n'
src/doc/rust-by-example/po/es.po:2379: 'msgid' and 'msgstr' entries do not both end with '\n'
src/doc/rust-by-example/po/es.po:2387: 'msgid' and 'msgstr' entries do not both end with '\n'
src/doc/rust-by-example/po/es.po:2401: 'msgid' and 'msgstr' entries do not both end with '\n'
src/doc/rust-by-example/po/es.po:2409: 'msgid' and 'msgstr' entries do not both end with '\n'
src/doc/rust-by-example/po/es.po:2425: 'msgid' and 'msgstr' entries do not both end with '\n'
src/doc/rust-by-example/po/es.po:2492: 'msgid' and 'msgstr' entries do not both end with '\n'
src/doc/rust-by-example/po/es.po:2709: 'msgid' and 'msgstr' entries do not both end with '\n'
src/doc/rust-by-example/po/es.po:2795: 'msgid' and 'msgstr' entries do not both end with '\n'
src/doc/rust-by-example/po/es.po:2799: 'msgid' and 'msgstr' entries do not both end with '\n'
src/doc/rust-by-example/po/es.po:2865: 'msgid' and 'msgstr' entries do not both end with '\n'
src/doc/rust-by-example/po/es.po:2869: 'msgid' and 'msgstr' entries do not both end with '\n'
src/doc/rust-by-example/po/es.po:2885: 'msgid' and 'msgstr' entries do not both end with '\n'
src/doc/rust-by-example/po/es.po:2947: 'msgid' and 'msgstr' entries do not both end with '\n'
msgfmt: found 17 fatal errors
gettext: src/doc/rust-by-example/po/zh.po:936: keyword "Ctrl" unknown
src/doc/rust-by-example/po/zh.po:936:42: syntax error
src/doc/rust-by-example/po/zh.po:986:15: syntax error
src/doc/rust-by-example/po/zh.po:1082:11: syntax error
src/doc/rust-by-example/po/zh.po:1082: keyword "x" unknown
src/doc/rust-by-example/po/zh.po:1542:35: syntax error
src/doc/rust-by-example/po/zh.po:3581:55: syntax error
src/doc/rust-by-example/po/zh.po:3831:132: syntax error
src/doc/rust-by-example/po/zh.po:4209:65: syntax error
src/doc/rust-by-example/po/zh.po:4798:30: syntax error
src/doc/rust-by-example/po/zh.po:5211:16: syntax error
src/doc/rust-by-example/po/zh.po:5258:18: syntax error
src/doc/rust-by-example/po/zh.po:5316:39: syntax error
src/doc/rust-by-example/po/zh.po:5661:25: syntax error
src/doc/rust-by-example/po/zh.po:7630:5: syntax error
src/doc/rust-by-example/po/zh.po:8231:5: syntax error
src/doc/rust-by-example/po/zh.po:8344:9: syntax error
src/doc/rust-by-example/po/zh.po:10060:80: syntax error
src/doc/rust-by-example/po/zh.po:11114:37: syntax error
src/doc/rust-by-example/po/zh.po:11357:81: syntax error
msgfmt: too many errors, aborting
      

Please ask the translator (identified by the Last-Translator field in the PO file), the language team (identified by the Language-Team field) or debian-i18n for a fix.