debian/lib/python/debian_linux/debian.py: Fix binNMU revision parsing

In VersionLinux, any binNMU version will currently match the
revision_other group in the regexp and therefore never be recognised
as an experimental, security, or backport version.  This is probably
harmless in practice because:

- binNMUs don't happen in those suites
- Only debian/bin/gencontrol.py cares about the linux_revision_other
  attribute, and it won't be run for a binNMU version

But let's fix it by matching the binNMU suffix separately.

debian/changelog

@@ -14,6 +14,7 @@ linux (4.16.3-1) UNRELEASED; urgency=medium
   * Set ABI to 1
   * [x86,arm64] Disable code signing for upload to unstable
   * debian/lib/python/debian_linux/debian.py: Fix binNMU changelog parsing
+  * debian/lib/python/debian_linux/debian.py: Fix binNMU revision parsing
 
   [ Vagrant Cascadian ]
   * [arm64] Add patches to support SATA on Tegra210/Jetson-TX1.

debian/lib/python/debian_linux/debian.py

@@ -181,9 +181,10 @@ class VersionLinux(Version):
     )?
     |
     (?P<revision_other>
-        [^-]+
+        [^-+]+
     )
 )
+(?:\+b\d+)?
 $
 """
     _version_linux_re = re.compile(_version_linux_rules, re.X)