tests: Improve quoting

* src/tests/lexgrog-backslash-dash-rhs, src/tests/lexgrog-basic,
src/tests/lexgrog-multiple-whatis, src/tests/man-deleted-directory,
src/tests/man-exact-section-matches,
src/tests/man-executable-page-on-path, src/tests/man-invalid-db-entry,
src/tests/man-language-specific-requests,
src/tests/man-mandatory-manpath, src/tests/man-missing-locales,
src/tests/man-override-dir, src/tests/man-recode-in-place,
src/tests/man-recode-suffix, src/tests/man-so-links-same-section,
src/tests/man-suffixed-extension,
src/tests/man-symlinks-with-matching-names,
src/tests/manconv-coding-tags, src/tests/manconv-guess-from-encoding,
src/tests/manconv-incomplete-char-at-eof,
src/tests/manconv-odd-combinations, src/tests/mandb-basic,
src/tests/mandb-bogus-symlink, src/tests/mandb-cachedir-tag,
src/tests/mandb-empty-page, src/tests/mandb-purge-updates-timestamp,
src/tests/mandb-regular-file-symlink-changes,
src/tests/mandb-symlink-beats-whatis-ref,
src/tests/mandb-symlink-target-timestamp,
src/tests/mandb-whatis-broken-link-changes,
src/tests/whatis-path-to-executable, src/tests/zsoelim-so-includes: Use
': "${var=default}"' idiom to assign default values rather than
': ${var=default}', pacifying shellcheck.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/tests/man-recode-in-place b/src/tests/man-recode-in-place
index bb75aa70..9d343e9c 100755
--- a/src/tests/man-recode-in-place
+++ b/src/tests/man-recode-in-place
@@ -2,10 +2,10 @@
 
 # Test man-recode's --in-place behaviour.
 
-: ${srcdir=.}
+: "${srcdir=.}"
 . "$srcdir/testlib.sh"
 
-: ${MAN_RECODE=man-recode}
+: "${MAN_RECODE=man-recode}"
 
 init