tests: more automated quote adjustment

Relax initial regexp to match more instances, but add a
filter to avoid some invalid conversions.  Run this:

git grep -l "\`[^']*'" tests | xargs perl -pi -e '$q=q"'\''";' \
  -e '$q="$q\\$q$q"; /(= ?\`|\`expr|\`echo|\Q$q\E)/ and next;' \
  -e ' s/\`([^'\''"]*?'\'')/'\''$1/g'
The last disjunct in the above (...) filter is to exempt
any line that contains this string: '\''
With quoting like that, converting a ` to ' is likely to cause trouble,
so we'll handle those manually.  Here are three examples where
the exemption is required:

  *': `link-to-dir/'\'': hard link not allowed for directory'*) ;;
  printf 'creating file `%s'\''\n' $f
  'mv: inter-device move failed: `%s'\'' to `%s'\'';'\

1 files changed, 1 insertions, 1 deletions

diff --git a/tests/chmod/no-x b/tests/chmod/no-x
index cc0d14268..19f439832 100755
--- a/tests/chmod/no-x
+++ b/tests/chmod/no-x
@@ -47,7 +47,7 @@ EOF
 compare exp out || fail=1
 
 cd a
-# This will fail with '`chmod: fts_read failed: Permission denied''
+# This will fail with ''chmod: fts_read failed: Permission denied''
 chmod a-x . b 2> /dev/null && fail=1
 # chmod must exit with status 1.
 # Due to a bug in coreutils-5.93's fts.c, chmod would provoke