Bug 1513216 - Don't collect build telemetry when 'mach' is ran from hg format-source. r=sheehan

Differential Revision: https://phabricator.services.mozilla.com/D14146

--HG--
extra : moz-landing-system : lando

build/mach_bootstrap.py

@@ -229,6 +229,10 @@ def bootstrap(topsrcdir, mozilla_dir=None):
         if depth != 1 or os.environ.get('MACH_MAIN_PID') != str(os.getpid()):
             return
 
+        # Don't write telemetry data for 'mach' when 'DISABLE_TELEMETRY' is set.
+        if os.environ.get('DISABLE_TELEMETRY') == '1':
+            return
+
         # We have not opted-in to telemetry
         if not context.settings.build.telemetry:
             return