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'\'';'\

2 files changed, 2 insertions, 2 deletions

diff --git a/tests/cp/fiemap-empty b/tests/cp/fiemap-empty
index 951d8e062..efa4b660d 100755
--- a/tests/cp/fiemap-empty
+++ b/tests/cp/fiemap-empty
@@ -48,7 +48,7 @@ fallocate -l 600MiB space.test ||
 
 # Disable this test on old BTRFS (e.g. Fedora 14)
 # which reports ordinary extents for unwritten ones.
-filefrag space.test || skip_ 'the 'filefrag` utility is missing'
+filefrag space.test || skip_ 'the 'filefrag' utility is missing'
 filefrag -v space.test | grep -F 'unwritten' > /dev/null ||
   skip_ 'this file system does not report empty extents as "unwritten"'
 
diff --git a/tests/cp/fiemap-perf b/tests/cp/fiemap-perf
index 3addfe1b2..e418728ee 100755
--- a/tests/cp/fiemap-perf
+++ b/tests/cp/fiemap-perf
@@ -34,7 +34,7 @@ timeout 10 truncate -s1T f || framework_failure_
 
 # Disable this test on old BTRFS (e.g. Fedora 14)
 # which reports (unwritten) extents for holes.
-filefrag f || skip_ 'the 'filefrag` utility is missing'
+filefrag f || skip_ 'the 'filefrag' utility is missing'
 filefrag f | grep -F ': 0 extents found' > /dev/null ||
   skip_ 'this file system reports extents for holes'