pexpects: Fix some escapes

Python has become stricter about unknown `\x` in strings, firing a
SyntaxWarning right now.

They need to be `\\x`.

tests/pexpects/commandline.py

@@ -42,7 +42,7 @@ sendline(
     "function handle_tilde; echo; echo '@GUARD:1@'; commandline -b; echo '@/GUARD:1@'; commandline -b ''; end"
 )
 expect_prompt()
-sendline("echo \en one \"two three\" four'five six'{7} 'eight~")
+sendline("echo \\en one \"two three\" four'five six'{7} 'eight~")
 expect_prompt("\r\n@GUARD:1@\r\n(.*)\r\n@/GUARD:1@\r\n")
 
 # printing the buffer with -o should remove quoting

tests/pexpects/complete-group-order.py

@@ -43,6 +43,6 @@ expect_prompt()
 send("fooc \t")
 
 expect_re(
-    "india\W+hotel\W+charlie\W+alpha\W+delta\W+kilo\r\n"
-    + "foxtrot\W+golf\W+echo\W+bravo\W+juliett\W+lima"
+    "india\\W+hotel\\W+charlie\\W+alpha\\W+delta\\W+kilo\r\n"
+    + "foxtrot\\W+golf\\W+echo\\W+bravo\\W+juliett\\W+lima"
 )

tests/pexpects/eval-stack-overflow.py

@@ -31,7 +31,7 @@ expect_re(
     + "\r\nin command substitution"
     + "\r\nfish: Unable to evaluate string substitution"
     + re.escape("\r\neval (string replace dog tiger -- $history[1])")
-    + "\r\n *\^~+\^\w*"
+    + "\r\n *\\^~+\\^\\w*"
 )
 expect_prompt()
 

tests/pexpects/history.py

@@ -108,13 +108,13 @@ expect_prompt("count hello 0\r\n")
 # sent above that matches).
 sendline("history delete -p 'echo hello'")
 expect_re("history delete -p 'echo hello'" + TO_END_SUFFIX)
-expect_re("\[1\] echo hello AGAIN" + TO_END_SUFFIX)
-expect_re("\[2\] echo hello again" + TO_END_SUFFIX)
+expect_re("\\[1\\] echo hello AGAIN" + TO_END_SUFFIX)
+expect_re("\\[2\\] echo hello again" + TO_END_SUFFIX)
 expect_re("Enter nothing to cancel the delete, or\r\n")
 expect_re("Enter one or more of the entry IDs or ranges like '5..12', separated by a space.\r\n")
 expect_re("For example '7 10..15 35 788..812'.\r\n")
 expect_re("Enter 'all' to delete all the matching entries.\r\n")
-expect_re("Delete which entries\? ")
+expect_re("Delete which entries\\? ")
 sendline("1")
 expect_prompt('Deleting history entry 1: "echo hello AGAIN"\r\n')
 
@@ -131,7 +131,7 @@ sendline(
 expect_prompt("count again 1\r\n")
 
 # Verify that the $history var has the expected content.
-sendline("echo history2=$history\[2\]")
+sendline("echo history2=$history[2]")
 expect_prompt("history2=echo count AGAIN .*\r\n")
 
 # Verify that history search is case-insensitive by default