Fix File source handler to accept single extensions option

Author: uasi

Changes

@@ -7,6 +7,7 @@ Revision history for Test-Harness
         - Avoid non-deterministic source handling, make a SourceHandler tie an
           error. (Michael Schwern, Leon Timmermans)
         - Fix and simplify MSWin32 colorization (Roy Ivy III)
+        - Fix file source handler to accept single extensions option (Tomoki Aonuma)
         - Spelling fixes (Brian Wightman)
 
 3.39    06-04-2017

lib/TAP/Parser/SourceHandler/File.pm

@@ -71,7 +71,8 @@ sub can_handle {
     return 0.9 if $file->{lc_ext} eq '.tap';
 
     if ( my $exts = $config->{extensions} ) {
-        return 0.9 if grep { lc($_) eq $file->{lc_ext} } @$exts;
+        my @exts = ref $exts eq 'ARRAY' ? @$exts : $exts;
+        return 0.9 if grep { lc($_) eq $file->{lc_ext} } @exts;
     }
 
     return 0;