Add a bitbake argument to disable variable history tracking for `bitbake -e`, as history tracking massively increases memory usage

bitbake-add-no-var-tracking-arg.patch

diff --git i/lib/bb/cookerdata.py w/lib/bb/cookerdata.py
index 722d860..d48ef14 100644
--- i/lib/bb/cookerdata.py
+++ w/lib/bb/cookerdata.py
@@ -42,7 +42,9 @@ class ConfigParameters(object):
         self.options.pkgs_to_build = targets or []
 
         self.options.tracking = False
-        if hasattr(self.options, "show_environment") and self.options.show_environment:
+        if (hasattr(self.options, "show_environment") and
+                self.options.show_environment and
+                not self.options.no_variable_tracking):
             self.options.tracking = True
 
         for key, val in self.options.__dict__.items():
diff --git i/lib/bb/data_smart.py w/lib/bb/data_smart.py
index d6dd698..4f39de5 100644
--- i/lib/bb/data_smart.py
+++ w/lib/bb/data_smart.py
@@ -317,8 +317,8 @@ class VariableHistory(object):
                 o.write("# pre-expansion value:\n")
                 o.write('#   "%s"\n' % (commentVal))
         else:
-            o.write("#\n# $%s\n#   [no history recorded]\n#\n" % var)
-            o.write('#   "%s"\n' % (commentVal))
+            if oval != val:
+                o.write('# %s=%s\n' % (var, commentVal))
 
     def get_variable_files(self, var):
         """Get the files where operations are made on a variable"""
diff --git i/lib/bb/main.py w/lib/bb/main.py
index b3cd2cf..c9fa505 100755
--- i/lib/bb/main.py
+++ w/lib/bb/main.py
@@ -206,6 +206,9 @@ class BitBakeConfigParameters(cookerdata.ConfigParameters):
                           help="Show the global or per-recipe environment complete with information"
                                " about where variables were set/changed.")
 
+        parser.add_option("--no-variable-tracking", action="store_true",
+                          help="Disable variable tracking, which is enabled by default when using --environment/-e. The variable tracking feature adds variable history support to the -e output, but greatly increases memory usage")
+
         parser.add_option("-g", "--graphviz", action="store_true", dest="dot_graph", default=False,
                           help="Save dependency tree information for the specified "
                                "targets in the dot syntax.")