Context IDs replaced in .PO file

The Context ID variable of strings in .PO files are messed up if they contain multiple column characters. This results in a corrupt .PO file.

Example:

#: block:2:title
msgid "Welcome!"
msgstr ""

...will be saved as:

#: block:2:0
msgid "Welcome!"
msgstr "Bienvenue!"

Notice the `block:2:title` becoming `block:2:0`

What steps will reproduce the problem?

1. Open a .PO file like those created by Drupal's i18n module.
2. Click on any of the strings inside. Edit, or not, some of the translations.
3. Save.

What is the expected output? What do you see instead?
Edited strings with the same IDs as the original.

What version of the product are you using? On what operating system?
4.6 on Mac OS 10.6.

—

Alternatively, I tried regex-ing out the column characters from the file before editing in Linguist, but the results were worse.

#: block•2•title
msgid "Welcome!"
msgstr ""

...would become:

msgid "Welcome!"
msgstr "Bienvenue!"

The entire context line is removed!