Avoid failed history erase mode

OBS-URL: https://build.opensuse.org/package/show/shells/tcsh?expand=0&rev=157

tcsh-6.24.10-history-merge.dif

@@ -1,19 +1,27 @@
 ---
- sh.hist.c |    4 ++--
+ sh.hist.c |    5 +++--
- 1 file changed, 2 insertions(+), 2 deletions(-)
+ 1 file changed, 3 insertions(+), 2 deletions(-)
 
 --- sh.hist.c
-+++ sh.hist.c	2023-07-21 09:38:31.303857784 +0000
++++ sh.hist.c	2023-07-21 12:21:55.518480015 +0000
 @@ -64,7 +64,7 @@ static	void	hfree	(struct Hist *);
  
  /* #define DEBUG_HIST 1 */
  
 -static const int fastMergeErase = 1;
-+static const int fastMergeErase = 0;	/* Was true, now false to merge even with full history list */
++static int fastMergeErase = 1;
  static unsigned histCount = 0;		/* number elements on history list */
  static int histlen = 0;
  static struct Hist *histTail = NULL;     /* last element on history list */
-@@ -1393,7 +1393,7 @@ loadhist(Char *fname, int mflg)
+@@ -1321,6 +1321,7 @@ rechist(Char *xfname, int ref)
+ 	}
+ 
+ 	if (merge) {
++	    fastMergeErase = 0;	/* Was true, now false to merge even with full history list */
+ 	    jmp_buf_t osetexit;
+ 	    if (lock) {
+ #ifndef WINNT_NATIVE
+@@ -1393,7 +1394,7 @@ loadhist(Char *fname, int mflg)
      /* During history merging (enthist sees mflg set), we disable management of
       * Hnum and Href (because fastMergeErase is true).  So now reset all the
       * values based on the final ordering of the history list. */