run-tests: detect when hghave fails to check for a feature and fail test
hghave exitcode != 0 might mean that hghave failed to check for feature
avaibility. Detect those cases, and fail the test, instead of skipping it.
adding a
now at: a.patch
applying b.patch
applying c.patch
now at: c.patch
now at: b.patch
% Using index
now at: a.patch
applying b.patch
applying c.patch
now at: c.patch
% No warnings when using index
now at: b.patch
applying c.patch
applying bug314159
now at: bug314159
% Detect ambiguous non-index
patch name "14" is ambiguous:
bug314159
bug141421
abort: patch 14 not in series