[glob] Eliminate two assertions in _GlobUnescape.

- Fixes #698
- Fixes fallout from #695 (failing test in spec/var-sub-quote)

There is still a different failing test case to remind us to overhaul
this code.  And we still need to fix issue #291 too.

This area of the code needs a bunch of work.

osh/glob_.py

@@ -10,16 +10,18 @@
     glob_part_e, glob_part, glob_part_t,
     glob_part__Literal, glob_part__Operator, glob_part__CharClass,
 )
-from core import util
 from core.pyutil import stderr_line
-#from core.util import log
+from core import util
+from core.util import log
 from frontend import match
 
 from typing import List, Tuple, cast, TYPE_CHECKING
 if TYPE_CHECKING:
   from core import optview
   from frontend.match import SimpleLexer
 
+_ = log
+
 
 def LooksLikeGlob(s):
   # type: (str) -> bool
@@ -125,14 +127,19 @@ def GlobUnescape(s):  # used by cmd_eval
   n = len(s)
   while i < n:
     c = s[i]
-    if c == '\\':
-      assert i != n - 1, 'Trailing backslash: %r' % s
+    if c == '\\' and i != n - 1:
+      # Suppressed this to fix bug #698, #628 is still there.
+      #assert i != n - 1, 'Trailing backslash: %r' % s
       i += 1
       c2 = s[i]
       if c2 in GLOB_META_CHARS:
         unescaped.append(c2)
       else:
-        raise AssertionError("Unexpected escaped character %r" % c2)
+        #raise AssertionError("Unexpected escaped character %r" % c2)
+        # Hack to prevent crash for now.  Need to rewrite this.
+        # Fell out of the fix to issue #695 to use _DQ_BACKSLASH in VS_ArgDQ.
+        #unescaped.append(c)
+        unescaped.append(c2)
     else:
       unescaped.append(c)
     i += 1

spec/var-sub-quote.test.sh

@@ -161,7 +161,9 @@ argv.py ${foo%d\'}
 #### Strip a string with single quotes, double quoted
 foo="'a b c d'"
 argv.py "${foo%d\'}"
-## stdout: ["'a b c "]
+## STDOUT:
+["'a b c "]
+## END
 
 #### The string to strip is space sensitive
 foo='a b c d'

test/spec.sh

@@ -321,7 +321,7 @@ comments() {
 }
 
 word-split() {
-  sh-spec spec/word-split.test.sh --osh-failures-allowed 8 \
+  sh-spec spec/word-split.test.sh --osh-failures-allowed 7 \
     ${REF_SHELLS[@]} $OSH_LIST "$@"
 }