fixup(BSS2): stablize BSS-2 operation

This introduces stabilizing fixes to support error counter overflows (for long-lasting experiments), lowers JTAG operation frequency to robustify readout of, e.g., chip version information.

packages/build-brainscales/package.py

@@ -15,6 +15,13 @@ import spack.build_environment
 class BuildBrainscales(WafPackage):
     """Common stuff for BrainScaleS packages..."""
 
+    version(
+        "9.0-a6",
+        git="https://github.com/electronicvisions/releases-ebrains",
+        tag="ebrains-9.0-a6",
+        commit="e9b6746edb5e8465ae2848556b70e4edd555182e",
+        submodules=True,
+    )
     version(
         "9.0-a5",
         git="https://github.com/electronicvisions/releases-ebrains",
@@ -31,6 +38,7 @@ class BuildBrainscales(WafPackage):
     )
 
     # common dependencies of BuildBrainscales-derived packages
+    depends_on('oppulance@9.0-a6', when='@9.0-a6', type=('build', 'link', 'run', 'test'))
     depends_on('oppulance@9.0-a5', when='@9.0-a5', type=('build', 'link', 'run', 'test'))
     depends_on('oppulance@9.0-a4', when='@9.0-a4', type=('build', 'link', 'run', 'test'))