Fix bugs, inefficiencies and bad style in regexps

Found by relint.  See discussion at
https://lists.gnu.org/archive/html/emacs-devel/2020-04/msg00265.html

* lisp/org/org-table.el (org-table-finish-edit-field):
* lisp/arc-mode.el (archive-rar-summarize):
Avoid wrapped subsumption in repeated sequences.
* lisp/erc/erc-dcc.el (erc-dcc-ctcp-query-send-regexp): Replace
inefficient repeated empty-matching expression with a plain greedy
form.
(erc-dcc-handle-ctcp-send): Adjust group numbers.
* lisp/net/puny.el (puny-encode-domain): Fix fast-path shortcut
pattern so that it actually works as intended.
* lisp/progmodes/gdb-mi.el (gdb-control-commands-regexp):
* lisp/vc/diff-mode.el (diff-imenu-generic-expression):
Remove superfluous backslashes.
* lisp/progmodes/scheme.el (scheme-imenu-generic-expression):
Correct confused definition-matching pattern which would match more
than intended.
* lisp/textmodes/sgml-mode.el (sgml-tag-name-re): Avoid inefficient
matching by using the fact that the first character cannot match the
last char of sgml-name-re.

1 files changed, 1 insertions, 1 deletions

diff --git a/lisp/vc/diff-mode.el b/lisp/vc/diff-mode.el
index da2d5ed50e4..d194d6c0a0e 100644
--- a/lisp/vc/diff-mode.el
+++ b/lisp/vc/diff-mode.el
@@ -484,7 +484,7 @@ and the face `diff-added' for added lines.")
   ;; Prefer second name as first is most likely to be a backup or
   ;; version-control name.  The [\t\n] at the end of the unidiff pattern
   ;; catches Debian source diff files (which lack the trailing date).
-  '((nil "\\+\\+\\+\\ \\([^\t\n]+\\)[\t\n]" 1) ; unidiffs
+  '((nil "\\+\\+\\+ \\([^\t\n]+\\)[\t\n]" 1) ; unidiffs
     (nil "^--- \\([^\t\n]+\\)\t.*\n\\*" 1))) ; context diffs
 
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