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/mv/i-1 b/tests/mv/i-1
index 20b6ad7b9..5895137da 100755
--- a/tests/mv/i-1
+++ b/tests/mv/i-1
@@ -30,7 +30,7 @@ my @Tests =
      # Make sure a 'n' reply to 'mv -i...' aborts the move operation.
      [$test_a, '-i',
       {IN => {src => "a\n"}}, {IN => {dst => "b\n"}}, '<', {IN => "n\n"},
-      {ERR => "mv: overwrite `dst'? "},
+      {ERR => "mv: overwrite 'dst'? "},
       {POST => sub { -r 'src' or die "test $test_a failed\n"}},
       {EXIT => 0},
      ],