generate-pot-files.sh sometimes generates files with multiple headers

[Dylan McCall]

generate-pot-files.sh is supposed to generate a single .pot file for each flavour, and it does this by making one for each slide and then merging them together. Usually we get something like this:

 #, fuzzy
 msgid ""
 msgstr ""
 "Project-Id-Version: PACKAGE VERSION\n"
 "POT-Creation-Date: 2012-10-01 08:19-0600\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <email address hidden>\n"
 "Language: \n"
 "MIME-Version: 1.0\n"
 "Content-Type: text/plain; charset=UTF-8\n"
 "Content-Transfer-Encoding: 8bit\n"

 #. type: Content of: <div><h1>
 #: slideshows/lubuntu/slides/00_welcome.html:1
 msgid "Welcome to Lubuntu 12.10"
 msgstr ""

Sometimes, we get something like this:

 #, fuzzy
 msgid ""
 msgstr ""
 "#-#-#-#-# 00_welcome.html.pot (PACKAGE VERSION) #-#-#-#-#\n"
 "Project-Id-Version: PACKAGE VERSION\n"
 "POT-Creation-Date: 2012-09-25 09:33-0300\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <email address hidden>\n"
 "Language: \n"
 "MIME-Version: 1.0\n"
 "Content-Type: text/plain; charset=UTF-8\n"
 "Content-Transfer-Encoding: 8bit\n"
 "#-#-#-#-# 01_lxde.html.pot (PACKAGE VERSION) #-#-#-#-#\n"
 "Project-Id-Version: PACKAGE VERSION\n"
 "POT-Creation-Date: 2012-09-25 09:33-0300\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <email address hidden>\n"
 "Language: \n"
 "MIME-Version: 1.0\n"
 "Content-Type: text/plain; charset=UTF-8\n"
 "Content-Transfer-Encoding: 8bit\n"
 "#-#-#-#-# 02_browser.html.pot (PACKAGE VERSION) #-#-#-#-#\n"
 "Project-Id-Version: PACKAGE VERSION\n"
 "POT-Creation-Date: 2012-09-25 09:33-0300\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <email address hidden>\n"
 "Language: \n"
 "MIME-Version: 1.0\n"
 "Content-Type: text/plain; charset=UTF-8\n"
 "Content-Transfer-Encoding: 8bit\n"
 "#-#-#-#-# 03_office.html.pot (PACKAGE VERSION) #-#-#-#-#\n"
 "Project-Id-Version: PACKAGE VERSION\n"
 "POT-Creation-Date: 2012-09-25 09:35-0300\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <email address hidden>\n"
 "Language: \n"
 "MIME-Version: 1.0\n"
 "Content-Type: text/plain; charset=UTF-8\n"
 "Content-Transfer-Encoding: 8bit\n"
 "#-#-#-#-# 04_media.html.pot (PACKAGE VERSION) #-#-#-#-#\n"
 "Project-Id-Version: PACKAGE VERSION\n"
 "POT-Creation-Date: 2012-09-25 09:35-0300\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <email address hidden>\n"
 "Language: \n"
 "MIME-Version: 1.0\n"
 "Content-Type: text/plain; charset=UTF-8\n"
 "Content-Transfer-Encoding: 8bit\n"
 "#-#-#-#-# 05_social.html.pot (PACKAGE VERSION) #-#-#-#-#\n"
 "Project-Id-Version: PACKAGE VERSION\n"
 "POT-Creation-Date: 2012-09-25 09:35-0300\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <email address hidden>\n"
 "Language: \n"
 "MIME-Version: 1.0\n"
 "Content-Type: text/plain; charset=UTF-8\n"
 "Content-Transfer-Encoding: 8bit\n"
 "#-#-#-#-# 06_lsc.html.pot (PACKAGE VERSION) #-#-#-#-#\n"
 "Project-Id-Version: PACKAGE VERSION\n"
 "POT-Creation-Date: 2012-09-25 09:35-0300\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <email address hidden>\n"
 "Language: \n"
 "MIME-Version: 1.0\n"
 "Content-Type: text/plain; charset=UTF-8\n"
 "Content-Transfer-Encoding: 8bit\n"
 "#-#-#-#-# 07_help.html.pot (PACKAGE VERSION) #-#-#-#-#\n"
 "Project-Id-Version: PACKAGE VERSION\n"
 "POT-Creation-Date: 2012-09-25 09:35-0300\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <email address hidden>\n"
 "Language: \n"
 "MIME-Version: 1.0\n"
 "Content-Type: text/plain; charset=UTF-8\n"
 "Content-Transfer-Encoding: 8bit\n"
 "#-#-#-#-# 08_thanks.html.pot (PACKAGE VERSION) #-#-#-#-#\n"
 "Project-Id-Version: PACKAGE VERSION\n"
 "POT-Creation-Date: 2012-09-25 09:35-0300\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <email address hidden>\n"
 "Language: \n"
 "MIME-Version: 1.0\n"
 "Content-Type: text/plain; charset=UTF-8\n"
 "Content-Transfer-Encoding: 8bit\n"

 #. type: Content of: <div><h1>
 #: slideshows/lubuntu/slides/00_welcome.html:1
 msgid "Welcome to Lubuntu 12.10"
 msgstr ""

The latter seems to happen with no changes to the files being translated.