update manpage last-modified from git via pre-export hook

Never updating this information is wrong, updating it automatically
isn't super correct either, but it seems conventional to have it and
updating it more often than needed seems better than updating it never.

Git-Dch: Ignore

doc/apt-cache.8.xml

@@ -14,7 +14,7 @@
    &apt-email;
    &apt-product;
    <!-- The last update date -->
-   <date>2012-06-09T00:00:00Z</date>
+   <date>2015-10-27T00:00:00Z</date>
  </refentryinfo>
  
  <refmeta>

doc/apt-cdrom.8.xml

@@ -13,7 +13,7 @@
    &apt-author.team;
    &apt-email;
    &apt-product;
-   <date>2012-06-09T00:00:00Z</date>
+   <date>2013-11-30T00:00:00Z</date>
  </refentryinfo>
 
  <refmeta>

doc/apt-config.8.xml

@@ -14,7 +14,7 @@
    &apt-email;
    &apt-product;
    <!-- The last update date -->
-   <date>2012-06-09T00:00:00Z</date>
+   <date>2013-11-30T00:00:00Z</date>
  </refentryinfo>
  
  <refmeta>

doc/apt-extracttemplates.1.xml

@@ -14,7 +14,7 @@
    &apt-email;
    &apt-product;
    <!-- The last update date -->
-   <date>2012-06-09T00:00:00Z</date>
+   <date>2014-03-27T00:00:00Z</date>
  </refentryinfo>
  
  <refmeta>

doc/apt-ftparchive.1.xml

@@ -14,7 +14,7 @@
    &apt-email;
    &apt-product;
    <!-- The last update date -->
-   <date>2012-06-09T00:00:00Z</date>
+   <date>2015-10-28T00:00:00Z</date>
  </refentryinfo>
  
  <refmeta>

doc/apt-get.8.xml

@@ -14,7 +14,7 @@
    &apt-email;
    &apt-product;
    <!-- The last update date -->
-   <date>2012-06-09T00:00:00Z</date>
+   <date>2015-08-14T00:00:00Z</date>
  </refentryinfo>
  
  <refmeta>

doc/apt-key.8.xml

@@ -13,7 +13,7 @@
    &apt-email;
    &apt-product;
    <!-- The last update date -->
-   <date>2012-06-09T00:00:00Z</date>
+   <date>2015-10-15T00:00:00Z</date>
  </refentryinfo>
 
  <refmeta>

doc/apt-secure.8.xml

@@ -13,7 +13,7 @@
    &apt-email;
    &apt-product;
    <!-- The last update date -->
-   <date>2015-10-14T00:00:00Z</date>
+   <date>2015-10-15T00:00:00Z</date>
  </refentryinfo>
 
  <refmeta>

doc/apt-sortpkgs.1.xml

@@ -14,7 +14,7 @@
    &apt-email;
    &apt-product;
    <!-- The last update date -->
-   <date>2012-06-09T00:00:00Z</date>
+   <date>2013-11-30T00:00:00Z</date>
  </refentryinfo>
  
  <refmeta>

doc/apt.8.xml

@@ -13,7 +13,7 @@
    &apt-email;
    &apt-product;
    <!-- The last update date -->
-   <date>2013-11-25T00:00:00Z</date>
+   <date>2015-10-20T00:00:00Z</date>
  </refentryinfo>
  
  <refmeta>

doc/apt.conf.5.xml

@@ -19,7 +19,7 @@
    &apt-email;
    &apt-product;
    <!-- The last update date -->
-   <date>2012-06-09T00:00:00Z</date>
+   <date>2015-10-16T00:00:00Z</date>
  </refentryinfo>
  
  <refmeta>

doc/apt_preferences.5.xml

@@ -13,7 +13,7 @@
    &apt-email;
    &apt-product;
    <!-- The last update date -->
-   <date>2012-06-09T00:00:00Z</date>
+   <date>2015-08-15T00:00:00Z</date>
  </refentryinfo>
 
  <refmeta>

doc/sources.list.5.xml

@@ -14,7 +14,7 @@
    &apt-email;
    &apt-product;
    <!-- The last update date -->
-   <date>2014-01-18T00:00:00Z</date>
+   <date>2015-09-14T00:00:00Z</date>
  </refentryinfo>
  
  <refmeta>

prepare-release

@@ -56,6 +56,14 @@ if [ "$1" = 'pre-export' ]; then
 	sed -i -e "s/^PACKAGE_VERSION=\".*\"$/PACKAGE_VERSION=\"${VERSION}\"/" configure.ac
 	sed -i -e "s/^<!ENTITY apt-product-version \".*\">$/<!ENTITY apt-product-version \"${VERSION}\">/" doc/apt-verbatim.ent
 
+	# update the last-modification field of manpages based on git changes
+	grep --files-with-matches '<date>' doc/*.xml | while read file; do \
+		LASTMOD="$(date -d "@$(git log --format='%at' --max-count=1 --invert-grep --fixed-strings --grep 'review
+typo
+Git-Dch: Ignore' "$file")" '+%Y-%m-%dT00:00:00Z')"
+		sed -i -e "s#^\([ ]\+\)<date>.*</date>\$#\1<date>$LASTMOD</date>#" "$file"
+	done
+
 	if [ "$(date +%Y-%m-%d)" != "$(grep --max-count=1 '^"POT-Creation-Date: .*\n"$' po/apt-all.pot | cut -d' ' -f 2)" -o \
 	     "$(date +%Y-%m-%d)" != "$(grep --max-count=1 '^"POT-Creation-Date: .*\n"$' doc/po/apt-doc.pot | cut -d' ' -f 2)" ]; then
 		echo >&2 'POT files are not up-to-date. Execute »make update-po« for you…'
@@ -63,7 +71,7 @@ if [ "$1" = 'pre-export' ]; then
 	fi
 elif [ "$1" = 'post-build' ]; then
 	if [ "$DISTRIBUTION" != "UNRELEASED" ]; then
-		echo >&2 "REMEMBER: Tag this release with »git tag ${VERSION}« if you are satisfied"
+		echo >&2 "REMEMBER: Tag this release with »git tag -s ${VERSION}« if you are satisfied"
 	else
 		echo >&2 'REMEMBER: Change to a valid distribution before release'
 	fi
@@ -160,7 +168,7 @@ else
 	echo >&1 "Usage:\t$0 pre-export
 \t$0 post-build
 
-If you use »git buildpackage« you can leave these alone as they will
+If you use »gbp buildpackage« you can leave these alone as they will
 be run at the right places auto-magically. Otherwise you should use
 »pre-export« to update po and pot files as well as version numbering.
 »post-build« can be used to run some more or less useful checks later on.