empty locale string registered

After having installed and then shortly afterwards uninstalled the webfm module, I've discovered that it's created an empty locale string.
i.e.

mysql> SELECT * FROM locales_source WHERE source = '';
+------+----------------------------------------------------+-----------+--------+---------+
| lid  | location                                           | textgroup | source | version |
+------+----------------------------------------------------+-----------+--------+---------+
| 1431 | /mysite/?q=fr; sites/all/modules/webfm/js/webfm.js | default   |        | 6.14    |

After being exported to a .po file and then imported again, this seems to confuse the locale import routine, which thinks it's a header.

I'm not really sure if this is a bug in locale or in webfm; I've also filed #655048: Plural formula information blanked when importing a poorly-formed .po file.