UBUNTU: [Packaging] exact extend-diff-ignore matches

BugLink: http://bugs.launchpad.net/bugs/1693504

gen-auto-reconstruct script adds extend-diff-ignore options to
debian/source/options for symlinks not found in the orig tarball.

These options, however, are regular expressions, and match any part of a
file path. This may cause some files to be excluded from source when
they are not an exact match, but are a partial match to those symlinks.

Using beggining and end of string metacharacters fix the issue.

This problem was found in one of the derivatives, which contained a
symlink, whose name was a prefix for a directory in the same path,
leading that entire directory to be excluded from source.
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
[saf: escape literal '$' in string]
Acked-by: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

debian/scripts/misc/gen-auto-reconstruct

@@ -52,7 +52,7 @@ fi
 	git diff "$tag.." --raw --no-renames | awk '(/^:000000 120000/ && $5 == "A") { print $NF }' | \
 	while read name
 	do
-		echo "extend-diff-ignore=$name"
+		echo "extend-diff-ignore=^$name\$"
 	done
 ) >"$options.update"