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, 2 insertions, 2 deletions

diff --git a/tests/misc/nohup b/tests/misc/nohup
index e20a22c70..0fa1f3dc0 100755
--- a/tests/misc/nohup
+++ b/tests/misc/nohup
@@ -50,9 +50,9 @@ rm -f nohup.out err exp
 # change depending on whether stderr is redirected.
 nohup sh -c 'echo stdout; echo stderr 1>&2' >out || fail=1
 if test -t 2; then
-  test "`cat out|tr '\n' -`" = stdout-stderr- || fail=1
+  test "'cat out|tr '\n' -`" = stdout-stderr- || fail=1
 else
-  test "`cat out|tr '\n' -`" = stdout- || fail=1
+  test "'cat out|tr '\n' -`" = stdout- || fail=1
 fi
 # It must *not* exist.
 test -f nohup.out && fail=1