test: fix a few metacov exclusions

Author: nedbat

coverage/backward.py

@@ -78,7 +78,7 @@
 
 try:
     import reprlib
-except ImportError:             # pragma: part covered
+except ImportError:             # pragma: not covered
     # We need this on Python 2, but in testing environments, a backport is
     # installed, so this import isn't used.
     import repr as reprlib

metacov.ini

@@ -50,6 +50,7 @@ exclude_lines =
     # Lines that we can't run during metacov.
     pragma: no metacov
     pytest.mark.skipif\(env.METACOV
+    if not env.METACOV:
 
     # These lines only happen if tests fail.
     raise AssertionError
@@ -74,7 +75,6 @@ partial_branches =
     pragma: if failure
     pragma: part started
     if env.TESTING:
-    if not env.METACOV
     if .* env.JYTHON
     if .* env.IRONPYTHON