Fix detection of muslinux on CI.

src/gevent/testing/patched_tests_setup.py

@@ -1228,7 +1228,7 @@ if TRAVIS:
 if RUNNING_ON_MUSLLINUX:
     disabled_tests += [
         # This is supposed to *not* crash, but on the muslilnux image, it
-        # does crash.
+        # does crash (exitcode -11, ie, SIGSEGV)
         'test_threading.ThreadingExceptionTests.test_recursion_limit',
     ]
 

src/gevent/testing/sysinfo.py

@@ -129,7 +129,7 @@ RUNNING_ON_CI = RUNNING_ON_TRAVIS or RUNNING_ON_APPVEYOR
 RUNNING_ON_MANYLINUX = os.environ.get('GEVENT_MANYLINUX')
 # I'm not sure how to reliably auto-detect this, without
 # importing platform, something we don't want to do.
-RUNNING_ON_MUSLLINUX = os.environ.get('GEVENT_MANYLINUX_NAME') == 'musllinux'
+RUNNING_ON_MUSLLINUX = 'musllinux' in os.environ.get('GEVENT_MANYLINUX_NAME', '')
 
 if RUNNING_ON_APPVEYOR:
     # We can't exec corecext on appveyor if we haven't run setup.py in