hush: fix bkslash+newline handling and number validation in ${NN} and ${#NN}

Entering "${1a}" into interactive shell was making it exit.

function                                             old     new   delta
parse_dollar                                         824     958    +134
i_getch_and_eat_bkslash_nl                             -      44     +44
parse_expr                                           917     938     +21
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 2/0 up/down: 199/0)             Total: 199 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

3 files changed, 19 insertions, 1 deletions

diff --git a/shell/hush_test/hush-parsing/bkslash_newline4.right b/shell/hush_test/hush-parsing/bkslash_newline4.right
new file mode 100644
index 000000000..2110716d1
--- /dev/null
+++ b/shell/hush_test/hush-parsing/bkslash_newline4.right
@@ -0,0 +1,4 @@
+1:1
+22:22
+3:3
+Ok:0
diff --git a/shell/hush_test/hush-parsing/bkslash_newline4.tests b/shell/hush_test/hush-parsing/bkslash_newline4.tests
new file mode 100755
index 000000000..c8f5037c4
--- /dev/null
+++ b/shell/hush_test/hush-parsing/bkslash_newline4.tests
@@ -0,0 +1,14 @@
+set -- 1 22 333
+echo 1:$\
+1
+echo 22:$\
+{\
+2\
+}
+echo 3:$\
+{\
+#\
+3\
+}
+echo Ok:$\
+?
diff --git a/shell/hush_test/hush-vars/var6.right b/shell/hush_test/hush-vars/var6.right
index 40e67fdf5..5e28d2fab 100644
--- a/shell/hush_test/hush-vars/var6.right
+++ b/shell/hush_test/hush-vars/var6.right
@@ -1,2 +1,2 @@
-hush: invalid number '1q'
+hush: syntax error: unterminated ${name}
 hush: syntax error: unterminated ${name}