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/misc/timeout b/tests/misc/timeout
index cc1ad3d6e..d69e2f21b 100755
--- a/tests/misc/timeout
+++ b/tests/misc/timeout
@@ -42,7 +42,7 @@ test $? = 124 || fail=1
 timeout -s0 -k1 1 sleep 10
 test $? = 124 && fail=1
 
-# Ensure 'timeout` is immune to parent's SIGCHLD handler
+# Ensure 'timeout' is immune to parent's SIGCHLD handler
 # Use a subshell and an exec to work around a bug in FreeBSD 5.0 /bin/sh.
 (
   # ash doesn't support "trap '' CHLD"; it knows only signal numbers.