satisfy: Fix segmentation fault when called with empty argument

apt satisfy "" caused a segmentation fault because we were iterating
over the characters, checking if the next character was the end of
the string; when it could also be the current character.

Instead, check whether the next character is before the end of
the string, rather than identical to the end.

1 files changed, 1 insertions, 1 deletions

diff --git a/apt-private/private-source.cc b/apt-private/private-source.cc
index 3964ca48e..9b47ce31f 100644
--- a/apt-private/private-source.cc
+++ b/apt-private/private-source.cc
@@ -693,7 +693,7 @@ bool DoBuildDep(CommandLine &CmdL)
 
 	 // Reject '>' and '<' as operators, as they have strange meanings.
 	 bool insideVersionRestriction = false;
-	 for (auto C = Start; C + 1 != Stop; C++)
+	 for (auto C = Start; C + 1 < Stop; C++)
 	 {
 	    if (*C == '(')
 	       insideVersionRestriction = true;